Progesterone, 17-hydroxyprogesterone and four other 3-keto steroids were determined by high performance liquid chromatography with fluorescence detection. Each steroid was derivatized with 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene++ +-3- propionohydrazide (BODIPY FL hydrazide) and separated on a Wakosil 5C4 column with acetonitrile-water (7 + 3) as mobile phase. The limits of detection of progesterone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone and 17-methyltestosterone were 550-3700 fmol per 10 microliters injection (signal-to-noise ratio = 5) serum. The calibration curves were linear up to 1000 ng/ml serum. The proposed method was most sensitive among the available high performance liquid chromatographic methods after fluorescence and chemiluminescence pre-labeling with dansylhydrazine.