Sure, NYPD Blue is a great show, but can you dance to it?
Television theme songs have regularly hit the pop charts since 1959's ''Peter Gunn,'' but there's no guarantee a top-rated show will produce a top-selling record. Cheers' ''Where Everybody Knows Your Name'' rose only to No. 83 on the Billboard charts, and while Dynasty was also a ratings champ, its fanfarelike theme peaked at a mere No. 52.
And so it goes with NYPD Blue. Though veteran TV composer Mike Post has scored with other melodies his instrumentals for The Rockford Files and Hill Street Blues both reached No. 10 he's had no such luck with his NYPD Blue music. ''It's basically all percussion,'' Post says. ''I didn't think we'd have a hit single, and I was right.''
On the other hand, the series The Greatest American Hero attained mediocre ratings, yet ''Believe It or Not,'' which Post cowrote with Stephen Geyer, went to No. 2 in 1981 and stayed on the charts for 18 weeks.
Three shows have seen their tunes climb all the way to No. 1: S.W.A.T. (1975, 24 weeks on the charts), Welcome Back, Kotter (1976, 11 weeks), and Miami Vice (1985, 13 weeks). Other themes that cracked the top 25 include those of Hawaii Five-O (No. 4, 1969), The Young and the Restless (known as ''Nadia's Theme,'' No. 8, 1976), The Dukes of Hazzard (No. 21, 1980), Moonlighting (No. 23, 1987), Laverne & Shirley (No. 25, 1976), and Magnum, P.I. (No. 25, 1982).
Hit TV themes can bring new fans to established recording artists. The release of the Rembrandts' third album, LP, was pushed back two months to make room for their recording of ''I'll Be There for You,'' from the sitcom Friends. ''I thought someone was pulling our leg,'' says bassist Danny Wilde of the decision to add the song, but it has paid off: The album debuted at No. 26, and ''There for You'' has just been released as a single. TV-theme crooning worked similar wonders for Waylon Jennings (Dukes of Hazzard) and Al Jarreau (Moonlighting), and even Lawrence Welk once hopped on the bandwagon (My Three Sons).
Singer-songwriter John Sebastian already had a loyal following as a founder of the Lovin' Spoonful, but he might not have had a No. 1 hit with Welcome Back, Kotter if the show hadn't had a change of name. Originally, he was asked to write a song for a series called simply Kotter and, says Sebastian, ''nothing rhymes with that but otter.''
Then again, if the Captain & Tennille could have a hit with ''Muskrat Love''...
Jeffrey Cohen, with additional reporting by Kirsten McCumber