The aim of this study was to assess the linearity of pharmacokinetic of alfuzosin, administered by oral route, at the doses of 1, 2.5, and 5 mg to 12 young healthy volunteers. The pharmacokinetic parameters (tmax, Cmax, AUC, t1/2 beta) obtained from plasma alfuzosin concentrations after administration of the three doses show that pharmacokinetics of alfuzosin is linear in the range of doses 1-5 mg. Mean pharmacokinetic parameters of alfuzosin observed after 1, 2.5, and 5 mg were, respectively: tmax (h) 1.5 +/- 0.3, 1.1 +/- 0.2, 1.3 +/- 0.1; Cmax (ng ml-1) 2.6 +/- 0.3, 9.4 +/- 1.2, 13.5 +/- 1.0; AUC (ng ml-1 h) 17.7 +/- 2.9, 51.7 +/- 7.1, 99.0 +/- 14.1; t1/2 (h) 3.7 +/- 0.4, 3.9 +/- 0.2, 3.8 +/- 0.3. Cmax (corrected by the dose) obtained after 2.5 mg was significantly higher than those obtained after 1 and 5 mg. This difference seems to be due principally to the intraindividual variability. The absence of statistically significant difference on individual values of AUC corrected by the administered dose, supports the linearity of the pharmacokinetics of alfuzosin in the range of doses between 1 and 5 mg. Some postural hypotension, clinical criterion, was observed with a frequency increasing with the dose in these healthy subjects: 0 volunteers of 12 after 1 mg, 3 volunteers of 12 after 2.5 mg and 4 volunteers of 12 after 5 mg.