AbstractTen male patients with ultrasonographic evidence of an internal genital anomaly associated with ipsilateral renal agenesis are presented. The abnormalities consist of seminal vesicle agenesis in 4, seminal vesicle cyst in 3, Wolffian duct remnant in 2, and Mullerian duct remnant in 1. Such developmental defects are due to a primary anomaly of the mesonephros. Due to its capability of visualizing the lumbar and pelvic regions simultaneously, ultrasonography appears to be the first‐choice imaging modality for the screening of such genitourinary developmental malformation