OBJECTIVE To study the drainage proportions from the corpora cavernosa in defrosted human cadavers, as the veins related to penile erection were recently depicted to comprise the deep dorsal vein (DDV), a pair of cavernous veins (CVs) and two pairs of para-arterial veins (PAVs), as opposed to a single DDV between Buck's fascia and the tunica albuginea of the human penis. METHODS With no formalin fixation, 10 defrosted male human cadavers were used for this study. After injecting a 10% solution of colloid, and with the intracavernous pressure (ICP) fixed at 90 mmHg, the perfusion rate was recorded before and after the DDV, CVs and PAVs were removed, respectively. Finally, measurements were again recorded after penile arterial ligation. Cavernosography was used if required. RESULTS The mean (range) perfusion rate for maintaining the ICP at 90 mmHg was 30.2 (15.5-90.8) mL/min, whereas the arterial perfusion rate was 2.8 (0.3-3.9) mL/min. The mean (range) drainage proportion of the corpora cavernosa was 60.5 (50.3-69.7)%, 11.9 (5.8-22.9)% and 11.4 (5.2-15.0)% via the DDV, CVs and PAVs, respectively. The remaining drainage proportion was 15.6 (14.1-18.1)%. This study shows the separate drainage contributions of the DDV, CVs and PAVs to the corpora cavernosa of the human penis. CONCLUSIONS We conclude that the venous drainage system of the corpora cavernosa is much more complex than the previous depictions of it, and the consequent focus on a single DDV. This also shows the independent role of each venous system.