The video records of 264 males referred for videocystometry were reviewed retrospectively for evidence of urethroprostatic reflux. This was found in 11% of the cases with three distinct patterns; during bladder filling (27%); during voiding (50%), and during the 'stop test' (23%). All cases with filling reflux were unstable. Reflux at the time of the stop test was usually associated with prostatic or bladder neck obstruction. Voiding reflux occurred in a similar group of patients but there was often a clinical history of the previous surgical relief of obstruction or documented urinary infections. Recognition of this sign suggests the transmission of high pressures to the prostatic urethra and contrary to previous work is uncommonly associated with a history of lower urinary tract pain in cases where it may otherwise go unexplained.