This study investigated the effect of aqueous extract of cannabis sativa on lactate dehydrogenase activity (LDH) and creatinine level which are cardiac markers in male Wistar rats. The extract was administered orally at a single dose of 100, 200 and 400 mgkg-1 body weight to the experimental animals daily for 3 weeks. The increase in creatinine level and LDH activity was dose dependent. This present study showes that administration of C. sativa leaf extract at 100, 200 and 400 mgkg-1 increase the activity of LDH and creatinine level which may be deleterious to the heart.