The opening theme music to St. Elsewhere was composed by jazz pianist, film composer and twelve-time Grammy winner Dave Grusin. Grusin won an academy award for his original score for The Milagro Beanfield War (1988). He started getting TV scoring work in 1965, and got his first film score gig in 1967, shortly thereafter composing music for the soundtrack to The Graduate. Click these links for his IMDB profile and the Dave Grusin Archive.
Grusin's other notable TV themes include the shows The Ghost and Mrs. Muir, It Takes a Thief, The Name of the Game, The Bold Ones, Maude, Baretta, Good Times, and One Life to Live. His film scores include Three Days of the Condor, The Goodbye Girl, Heaven Can Wait, The Champ, ...And Justice For All, My Bodyguard, Absence of Malice, On Golden Pond, Tootsie, The Goonies, Ishtar, The Fabulous Baker Boys, Havana, The Bonfire of the Vanities, The Firm, Selena, and Hope Floats. (I don't feel like linking to all of these.)
It was the eighties, so as was common for the time, the theme music is performed entirely on synthesizers. I noticed that the theme for season five is a either a new recording or a remaster, probably a new recording; the synth sounds are less harsh, cleaner. The arrangement is exactly the same. There currently isn't a video for season five's theme on YouTube, so you'll have to take my word for it. Update, August 19, 2012: Season six's arrangement has a really annoying synth-triangle-like track that hits some really unpleasant high frequencies. By far my least favorite version.
The opening theme, season 1.
Here's a clip of the man himself, Dave Grusin, playing the theme on the piano with an ensemble of jazz musicians, the GRP All-Stars (GRP Records is the label he founded in the 70s). Featuring Lee Ritenour (guitar), Dave Valentin (flute), Ivan Lins (keyboards, vocals), Larry Williams (keyboards, sax), Abraham Laboriel (bass), and Carlos Vega (drums).
Here's a guy playing the St. Elsewhere theme with the pipe organ preset on a Roland Juno-G synth. I enjoy his arrangement. It's hard to capture all the polyphony with just ten fingers on two hands. On his YouTube post he warns that his improvised modulated outro at the end is his own improvisation.
This kid does a great arrangement of the St. Elsewhere theme for solo piano. I myself would have kept trying until I did a cleaner performance before putting it up on YouTube, but that's just me. And it's still good.
More Grusin...here are two pieces from his Oscar-winning score to The Milagro Beanfield War. I can totally understand why it won.
Grusin's theme music to Maude, with lyrics by Marilyn and Alan Bergman, performed by Donny Hathaway.
Grusin's theme to the Maude spinoff, Good Times, also with lyrics by Marilyn and Alan Bergman, sung by Jim Gilstrap and Blinky Williams.
Grusin and Morgan Ames's theme to Baretta, "Keep Your Eye on the Sparrow" sung by Sammy Davis, Jr. The first is from the actual Baretta opening credits; the second is an extended single that went to #1 in the Netherlands.
Grusin's main theme from On Golden Pond.
One more...here's Grusin's theme from Robert Altman's revisionist film noir Philip Marlowe movie, The Long Goodbye, with vocals by Jack Sheldon. This movie was featured in a film studies class I took. Various versions of the theme keep popping up through the film.
At one point during the film, Marlowe (Elliott Gould) is in a piano bar during the day, and there's a pianist practicing the tune because it's the latest hit that everyone wants to hear. That pianist is played by Jack Riley, who revived his character from The Bob Newhart Show, Mr. Carlin, in the season 4 St. Elsewhere episode, "Close Encounters", which crossed over the two series into the same fictional universe. He's in the psych ward when John Doe #6 decides that his true identity is Mary Richards from The Mary Tyler Moore Show, and he dubs Mr. Carlin as Rhoda.