Megan Terry's Viet Rock was created using this improvisational process. Scenes in Viet Rock were connected in "prelogical ways": a scene could be built from a tangent from the scene before, it could be connected psychologically, or it could be in counterpoint to the previous scene. Actors were asked to switch roles in the middle of a show, and frequently in mid-scene. In her stage directions for a Senate hearing scene in Viet Rock, Terry wrote, "The actors should take turns being senators and witnesses; the transformations should be abrupt and total. When the actor is finished with one character he becomes another, or just an actor."
Hair was designed in much the same way. Tom O'Horgan, the show's Broadway director, was intimately involved in the experimental theatre movement. In the transition to Broadway, O'Horgan and the writers rearranged scenes to increase the experimental aspects of the show. Hair asks its actors to assume several different characters throughout the course of the piece, and, as in Claude's psychedelic trip in Act 2, sometimes during the same scene. Both Hair and Viet Rock include rock music, borrowed heavily from mass media, and frequently break down the invisible "fourth wall" to interact with the audience. For example, in the opening number, the tribe mingles with audience members, and at the end of the show, the audience is invited on stage.
A 20th anniversary concert event was held in May 1988 at the United Nations General Assembly to benefit children with AIDS. The event was sponsored by First Lady Nancy Reagan with Barbara Walters giving the night's opening introduction. Rado, Ragni and MacDermot reunited to write nine new songs for the concert. The cast of 163 actors included former stars from various productions around the globe: Melba Moore, Ben Vereen, Treat Williams and Donna Summer, as well as guest performers Bea Arthur, Frank Stallone and Dr. Ruth Westheimer. Ticket prices ranged from $250 to $5,000 and the proceeds went to the United States Committee for UNICEF and the Creo Society's Fund for Children with AIDS.
A 1985 production of Hair mounted in Montreal was reportedly the 70th professional production of the musical. In November 1988, Michael Butler produced Hair at Chicago's Vic Theater to celebrate the shows' 20th anniversary. The production was well received and ran until February 1989. From 1990 to 1991, Pink Lace Productions ran a U.S. national tour of Hair that included stops in South Carolina, Georgia, Tennessee and Kentucky. After Ragni died in 1991, MacDermot and Rado continued to write new songs for revivals through the 1990s. Hair Sarajevo, AD 1992 was staged during the Siege of Sarajevo as an appeal for peace. Rado directed a $1 million, 11 city national tour in 1994 that featured actor Luther Creek. With MacDermot returning to oversee the music, Rado's tour celebrated the show's 25th anniversary. A small 1990 "bus and truck" production of Hair toured Europe for over 3 years, and Rado directed various European productions from 1995 to 1999.
A production opened in Australia in 1992 and a short-lived London revival starring John Barrowman and Paul Hipp opened at the Old Vic in London in 1993, directed by Michael Bogdanov. While the London production was faithful to the original, a member of the production staff said the reason it "flopped" was because the tribe consisted of "Thatcher's children who didn't really get it". Other productions were mounted around the world, including South Africa, where the show had been banned until the eradication of Apartheid. In 1996, Butler brought a month-long production to Chicago, employing the Pacific Musical Theater, a professional troupe in residence at California State University, Fullerton. Butler ran the show concurrently with the 1996 Democratic National Convention, echoing the last time the DNC was in Chicago: 1968. A 30th Anniversary Off-Off Broadway production was staged at Third Eye Repertory. It was directed by Shawn Rozsa.