Young weaning Swiss albino mice were orally administered leaf extract of Putranjiva roxburghii at 0.5, 1.0 or 2.0 g/kg body weight/day for seven consecutive days. The results showed that the leaf extract significantly induced mitosis-disruptive chromosomal changes in bone marrow cells. No change in the incidence of structural abnormalities was, however, noticed among the metaphase chromosomes. It is proposed that the extract might have interfered with the spindle and other proteins causing polyploidy, aneuploidy, c-mitosis, etc.