After leaving Santa Fe, Barry headed back to California to look for work, and was living in his Volkswagen van. "One morning I was over at Cass Elliot's house," he recalls, "and the phone rang. It was some people from New York looking for me, and they tracked me down at her house. They said they wanted me to come back and do a show called HAIR. John Sebastian was there, and we were sitting out at her swimming pool, and I said, 'What's HAIR?' He says, 'Oh, HAIR is a play about, well, it's kind of about what was happening in the streets of New York a couple of years ago.' I said, 'Well, I don't want to do something that was happening a couple of years ago. I want to do something happening today.'

     "Cass is leaning out the window of the house with the telephone, and I said, 'Tell him I don't want to do it.' She says, 'McGuire, why don't you just go back there and see what it's all about? They'll pay your ticket, you get to go back and see everybody, have a week in New York. You haven't done anything in a couple of years. Go do something.' and I said, 'Okay, tell them I'll...' She said, 'You come and tell them.' So, I went in and got on the phone, and I said, 'When do you want me?' They said, 'Tomorrow.' I said, 'Okay, leave me a ticket,' and I went down to the airport that evening, and I flew back and wound up doing HAIR for the next year." Barry joined the original cast six months into run of show. Initially, he played the role of Claude, then played Berger.

     After leaving the cast of HAIR, Barry returned to California. He showed up at Denny Doherty's house and stayed for the next year and a half. Eventually, Barry once again recorded for Lou Adler, now with Ode Records. The album was Barry McGuire and the Doctor, the Doctor being Eric Hord, who had been the lead guitarist for The Mamas and the Papas. Others joining Barry on the album were Chris Hillman, Bernie Leadon, Sneaky Pete, Michael Clarke, Billy Mundy, and Byron Berline. By this time, Barry's drug problem was way beyond any control. The album cover features Barry and Eric, who, in Barry's own words, looked like "two cadavers. Two dead human beings looking out of tombstone eyeballs, I mean just absolute end-of-the-road desolation. One of the guys that produced the album died of a drug overdose. The only reason we didn't die from an overdose is because we didn't make any money on the album."

     The extent of Barry's drug problem during the recording of this album is illustrated pretty well in a couple of stories Barry tells. They were doing huge amounts of cocaine during the recording sessions. One night as they left the studio, Barry dove into a trash can. The other guys got into the van, noticed Barry wasn't with them and wondered where he had gone. Barry says, "They looked around and my feet were sticking up out of the trash can. So they came and pulled me out and put me in the van and took me home." On another occasion, Barry was in Eric Hord's Volkswagen with several other people. Eric is doing about 65 MPH, and without Eric noticing, Barry slips out and gets up on the roof of the VW. "I was sitting up there cross-legged. Just wanted to get some fresh air. So I'm up there thinking, 'Yeah, this is better!'" Eventually, Eric notices Barry is missing and says, "Where's Mac?"
"Oh, he's on the roof," says one of the passengers.
"Up on the roof?!?"
So Eric slowly pulls the car over to the side of the road, gets out, looks up at Barry and says, "Mac! What're you doin' up there?"
"Just gettin' some fresh air," says Barry.
"Well, get down from there, Mac!"

     Barry McGuire and the Doctor was released in 1971. Although it received great critical acclaim, sales of the album were not as good as the reviews. In February of 1971, Barry became the father of twin boys. Helga Preller gave birth to Carlo and Jason on the morning of the L.A. earthquake. Barry says, "When Carlo and Jason came into the world, the earth shook!"

     Also that year, Barry appeared in his final feature film role. He played a biker named Scarf in Michel Levesque's bizarre horror flick, Werewolves on Wheels..
The plot has to do with a biker gang that gets on the wrong side of a group of Satanic monks, who curse two of the bikers, turning them into werewolves. The werewolves start killing off other members of the biker gang. Then, of course, the bikers seek revenge. One movie reviewer called this film "almost unwatchable." Barry agrees, calling it "a piece of trash." Made shortly before his conversion to Christianity, Barry was at an all-time low in his personal life while filming this flick. As he put it, "I was beyond the beyond. My life was in a total self-destruct mode. A lot of drugs, a lot of booze, getting more and more violent and more and more desolate inside because I'd been to the party. It's like you go to a carnival, and you go on all the rides, and you find the most fun ride, and then you go on that one over and over again until pretty soon you're bored with the whole thing. That's where I was at, that's where a lot of my friends were at. A lot of guys and girls I knew were taking their own lives. We'd done everything that was supposed to bring fulfillment, and nothing did. People that were much more famous, made much more money than me, had a much grander lifestyle than I had, were more miserable than I was. I thought, 'Well, what's the sense in going further in this direction, you know? I mean they're not happy. So, why should I continue along in this direction?' And it was right at that point in my life that this Jesus phenomenon started making itself known to me."