Aim: Many serious adverse effects of new xenobiotics are detected thorough toxicological studies. In this present study, the safety profile of C.articulata L. (Rutaceae) and M.aethiopicum (Celastraceae) leaf aqueous extracts was evaluated by acute and sub-chronic toxicity tests in male wistar rats. Methods: Acute oral toxicity was investigated in 8 weeks old Swiss mice (18-24g) that were divided in 4 groups (n=4mice) given extract doses ranging from 7,500-12,000 mg/kg and 15,000-22,500 mg/kg for M.aethiopicum and C.articulata respectively. In sub-chronic toxicity, male rats 8 weeks old weeks were divided into 8 groups (n=6). The two aqueous extracts were administered a single daily dose of 150, 300 and 450 mg/kg body weight orally for 21 consecutive days and at the 22th day, the organ weights, hematological, histological, serum biochemical parameters were determined. Results: The LD 50 of C.articulata and M. aethiopicum in Swiss mice were 18,985 mg/kg and 9,708 mg/kg body weight, respectively. General signs of toxicity due to large oral exposure to C.articulata were; hyper urination, diarrhea and hypo activity, while for M. aethiopicum were; Paralysis of hind limbs, defecation, respiratory distress, loss of balance and circling movement. Convulsions were observed in both extracts at death point. In