Eight apparently healthy male water monitor lizards (Varanus marmoratus), weighing 0.5-4.8 kg, were examined using an ultrasound machine equipped with a 5.0 MHz linear array scanner to determine the ultrasound appearance, dimensions and echo mean values of the urogenital organs. Based on snout to vent length, the eight animals were equally divided into small (<70 cm) and large (>70 cm) varanids. The kidneys of varanids were observed caudal to each gonad. They were elongated with hypoechoic parenchyma and hypoechoic to hyperechoic interlobular spaces. The testes of all eight males appeared as homogenous and moderately echogenic structures. The hemipenes appeared as anechoic structures with hypoechoic walls. The urinary bladder appeared as an elongated anechoic structure with hypoechoic walls. Significant differences in the length of left and right kidneys, length, width and circumference of left testes, length of hemipenes and length of the urinary bladder across sizes were observed. No differences were observed in the echo mean values of the different organs among small and large varanids. The data obtained in the study could serve as baseline values for evaluation of diseases and disorders of the male urogenital organs in water monitor lizards.