Aminopeptidases are enzymes that hydrolyze peptide bonds in N-terminal portion of protein and peptides, and also hydrolyze aminoacil-b-naphtylamides (AA-NA). They have medical and biological importance and the activity varies according to their cellular location. Modification of aminopeptidase also occur in the tumor formation, where the enzyme seem participate in the neovascularization (angiogenesis). However the precise functions of these enzymes in tumor cells and the relationship to prostate cancer remain unclear. The tumor cell invasion is a complex process involving cell adhesion, migration and degradation of tissue and extra cellular matrix barriers by different proteases secreted by tumor cells like Zn-dependent proteolytic enzymes, including aminopeptidase N (APN). The aim of this work was to purify and characterize aminopeptidases present in normal, BPH and prostate carcinoma and to verify the differences between them. Solubilization of aminopeptidases was obtained from Ultra Turrax homogenizer in 0.02 M sodium phosphate buffer pH 7.0. The supernatant of prostate's samples, centrifuged at 6000g/30 min / 4^o C, was submitted to ion exchange chromatography equilibrated and washed with 0.02 M NaPB, pH 7.0. From prostate carcinoma, PBH and normal, it were eluted, during a linear gradient of (0.02 to 0.2 M) NAPB, pH 7.0, two protein peaks with aminopeptidase activity upon AA-NA of Ala, Leu and Arg, P₁ (8,0 mS/cm) and P₂ (12,5 mS/cm). Beside these two peaks, the normal prostate eluted one third protein peak with aminopeptidase (P₃) in 15.7 mS/cm. Several pathologies may exhibit alterations in the aminopeptidases expression by inhibition through compound that don't inhibit the normal enzyme or exhibit different N-terminal sequence or by expressing another aminopeptidase. The aminopeptidases correspondent to P₃ founded in normal and not founded in BPH and prostate carcinoma may be inhibited in these pathologies. We can conclude that more studies about purification and characterization of aminopeptidases in these several important pathologies are necessary to the best understanding the prostatic physiopathology.