Abstract Transrectal ultrasound (TRUS) is an established investigation in benign and malignant prostatic disease though the level of reproducibility of TRUS volume measurements is not known. A group of observers in the UK and the USA who were participating in linked prospective studies of benign prostatic hyperplasia each carried out measurements during real-time scanning and on a series of static TRUS images. Results demonstrated good reproducibility for measurements of antero-posterior, transverse, and longitudinal dimensions of the prostate by an experienced UK urologist; only a minor degree of interobserver variation occurred in measurements made between experienced UK and USA observers. Using static images, USA observers obtained results that were in good agreement, whereas the UK observers, only two of whom used TRUS regularly, were in poor agreement with each other. This study demonstrates a high level of reproducibility for TRUS volume measurements performed by experienced observers.