Abstract: Toxicological study of Jatropha tanjorensis leaves was conducted by evaluating changes in weight, biochemical and ultrasonographic parameters of rabbits that have been administered varying concentrations (0, 5, 10 and 25%) of the ground leaves mixed with feed-mash for a period of 30 days. There was no significant difference (p<0.05) in weight of rabbits. Renal function tests revealed that there was a significant reduction of serum urea concentration in the male rabbits (p<0.05) from 38.33 in group C to 18.33 in group D. This suggests that the amount of J. tanjorensis plant powder used in this study could interfere positively with the filtration function of the kidney in rabbits. The ultrasound picture of kidney, heart and spleen showed no significant change from the control, where as there was reduction in the size of the liver with increased echogenicity when compared with the control. This may be an indication of hepatic toxicity.