A simple computer program consisting of 445 steps for a low-cost desk-top calculator (Hewlett-Packard 97) to be applied in chromatographic analyses of 17-ketosteroids and pregnanes from human urine samples is described. This program permits the calculation of peak factors following the chromatographic separation of an external standard mixture containing up to ten different fractions, the subsequent printout of the constants and their transcription to magnetic data cards for later retrieval when making calculations for unknown samples. After manual input of sample constants (such as total and aliquot volumes, recovery as determined by addition of radioactive tracer steroid, internal standard) and peak factors via the data card, the individual peak heights of the samples are automatically converted to milligrams of steroid in 24-h urine and each is stored separately. All fractions can be recalled later and printed out in the order of detection or can be transformed into several diagnostically valuable parameters such as the total sum of 17-ketosteroids and pregnanes excreted, the group sums of androgens, of 11-substituted steroids and of pregnanes, the individual percentages of both the fractions and the group sums, and the ratios of aetiocholanolone-androsterone and of pregnanetriol-pregnanediol. Finally, an extension subprogram can automatically generate a plot to illustrate the steroid excretion pattern in a comprehensive fashion.