The ethanol extract of leaves of the mangrove Aegiceras corniculatum Blanco (Myrsinaceae) was screened for its antinociceptive, antidiarrhoeal and cytotoxic activities. The extract produced significant writhing inhibition in acetic acid-induced writhing in mice at the oral dose of 250 and 500 mg/kg body weight (P < 0.001), which was comparable to the standard drug diclofenac sodium at the dose of 25 mg/kg of body weight. When tested for its antidiarrhoeal effects on castor oil induced diarrhoea in mice, it increased mean latent period and decreased the frequency of defecation significantly at the oral dose of 500 mg/kg body weight (P<0.05; P<0.01) comparable to the standard drug loperamide at the dose of 50 mg/kg of body weight. Moreover, when tested for toxicity using brine shrimp, the extract showed potent activity against the brine shrimp Artemia salina ($LC_{50}$ 10 mg/ml). The overall results tend to suggest the antinociceptive, antidiarrhoeal and cytotoxic activities of the extract.