Many authors agree with the importance of developing devices to measure penile rigidity. The devices that have been developed over recent years have defined penile rigidity in terms of stiffness. Penile stiffness, however, is believed to result from an increase in intracavernous pressure. The device presented here was therefore designed to estimate intracavernous pressure, rather than penile stiffness, as an index of penile rigidity. Validation of the penile cuff device was achieved by simultaneously recording penile cuff pressure and intracavernous pressure on patients undergoing artificial erections. The results showed a linear relationship and highly positive correlation coefficients between the 2 measures. The results demonstrate that the penile cuff may be used to estimate intracavernous pressure as an index of penile rigidity. The findings are discussed in terms of the possible applications of the cuff as a clinical tool to measure both penile tumescence and penile rigidity.