Methanolic extract of M. oleifera root was found to contain some alkaloids (total alkaloid 0.2%). Effects of multiple weekly (35, 46, 70 mg/kg) and daily therapeutic (3.5, 4.6, 7.0 mg/kg) i.p. doses of the crude extract (CE) on liver and kidney functions and hematological parameters in mice were studied. No alteration in hematological and biochemical parameters at low and moderate dose level of daily and low dose level of weekly treatment of the extract was observed. However, the extract at moderate dose level in weekly treatment changed serum aminotransferase and plasma cholesterol levels significantly. High dose in addition to the above parameters changed total bilirubin, non protein nitrogen, blood urea and plasma protein. High dose of daily treatment and moderate and high dose of weekly treatment of CE increased WBC count and decreased clotting time significantly. The results indicate that the weekly moderate and high dose (> 46 mg/kg body wt.) and daily/therapeutic high dose (7 mg/kg) of CE affects liver and kidney functions and hematological parameters whereas the weekly dose (3.5 mg/kg) and low and moderate daily/therapeutic dose (3.5 and 4.6 mg/kg) did not produce adverse effects on liver and kidney functions.