Semen sample analysis is routinely performed by microscopical evaluation and manual techniques by laboratory operators; the analysis is affected by a wide imprecision related to variability among observers, influencing its clinical validity. Our aim was to automate sperm analysis with the use of flow cytometry for evaluation of cell counts and typing and with the use of a new membrane-permeant nucleic acid stain for evaluation of sperm viability. Statistical analysis of the comparison between manual and automated methods for sperm counts was performed by the Bland and Altman method; the mean difference was 0.243 x 10(6) sperms/ mL. The precision of the flow cytometric analysis was evaluated with whole sperm; the between-run CV was 7.5% and the within-run CV was 2.5%. Data observed suggest that flow cytometric sperm analysis, with high precision and accuracy and low costs, can be proposed for routine use in clinical laboratories.