Vulvovaginal candidosis is one of the most frequent disorders in obstetrics and gynaecology. Candida albicans is commonly considered to be the true vaginopathic agent. The secreted acid proteinase might be especially relevant in the pathogenesis of vulvovaginal candidosis. A fluorometric determination of acid proteinase activity of clinical C. albicans isolates was carried out during the present work using fluorescamine. L-Leucyl-L-alanine was included as an internal standard and the results were expressed as nmoles of leucylalanine equivalents h(-1) per 2 x 10(4) cells. The 13 isolates were taken from non-diabetic, non-pregnant women aged 22-35 years with vulvovaginal candidosis. Candida albicans ATCC 44858 was used as a control. The proteinase activity in culture supernatants was detectable starting from the mid- to late- exponential phase of growth, peaked between 30 and 46 h, and then declined. The control had an activity of 2.72 nmol h(-1) per 2 x 10(4) cells, whereas eight of the samples had a lower activity (1.05 nmol h(-1) per 2 x 10(4) cells on average) and five of the samples had a higher activity (6.53 nmol h(-1) per 2 x 10(4) cells on average). The fluorometric determination of acid proteinase activity was found to be more reproducible and sensitive than the previously used spectrophotometric determinations.