It's been 35 years since Bonnie Koloc first appeared on the scene. Fresh faced and silver voiced, the Iowa-bred singer-songwriter headed to Chicago in 1968 to break into the folk and blues clubs that flourished in Old Town and on Rush Street and Lincoln Avenue and quickly became one of the city's top artists, headlining such fabled rooms as Mr. Kelly's and the Earl of Old Town. Her voice, with its bell-like upper register and dusky low tones, recalls Joan Baez and Judy Collins; earthy humor and passionate intensity simmer beneath her cool, elegant demeanor. In the early 80s Koloc relocated to New York, where she won praise for her lead performance in The Human Comedy, a Broadway musical by Hair composer Galt MacDermot based on William Saroyan's play. In 1986 she was part of one of the landmark productions in Chicago's off-Loop theater history, costarring with William Petersen (now of CSI) in the Brecht comedy Puntila and His Hired Man. Then, after a stint in Nashville, Koloc returned to her home state to pursue her first love, art: after finishing an art education degree at the University of Northern Iowa, she launched a career there as a printmaker, painter, and book illustrator. Still, Koloc retains a loyal following here as a singer: she's made several appearances in the last few years at the College of DuPage Arts Center, and this weekend she returns with a gig at FitzGerald's. Equally comfortable with pop, folk, blues, jazz, and gospel, she sings a repertoire that ranges from John Prine to Cole Porter and includes plenty of originals, including her signature tunes "Slow Dancing to the Blues," "If My Love Were a River," and "Roll Me on the Water." Backing her will be her longtime pianist Don Stille, bassist Al Erich, drummer Phil Gratteau, and reed man Steve Eisen, whose sublime call-and-response interplay with Koloc reflects a musical intimacy developed over 25 years. Performances are Friday, May 23, at 8 and 10:30 PM at FitzGerald's, 6615 Roosevelt in Berwyn. Tickets are $18; call 708-788-2118.