To maximize the total number of spermatozoa which can be retrieved from a testicular biopsy, four mechanical methods for preparation were compared. In all, 17 biopsies were divided into four equal fractions, which were weighed individually and prepared by rough shredding (control), fine mincing, vortexing and crushing (electrical Potter). After resuspension in an erythrocyte-lysing buffer, removal of the remaining tissue pieces, washing and centrifugation, the following parameters were evaluated: number of spermatozoa per 100 mg tissue, percentage motility, percentage vitality and percentage normal morphology (strict Kruger criteria). After further purification by discontinuous Percoll centrifugation, the same parameters were assessed again. This procedure was efficient in obtaining only spermatozoa in the final fraction. Before Percoll centrifugation, only minor differences between methods were observed. Percoll centrifugation generally resulted in a pronounced loss of sperm cells, partly because of the abnormal dimensions of the eliminated cells. After Percoll centrifugation, treatment of the testicular tissue by fine mincing was the most effective method in terms of the total number of motile spermatozoa and percentage normal morphology.