The present was carried out to evaluate the toxicity of methanolic leaf extract of Rhizophora mucronata (MERM) under in vivo and in vitro conditions. Mutagenicity of MERM (up to 4,000 μg/plate) evaluated by Salmonella/microsome assay (TA98, TA100, TA1535 and TA1538 strains), with or without metabolic activation showed no mutagenic effect in any of the tester strain. Evaluation of genotoxicity (comet assay) and cytotoxicity in PBMC revealed that MERM showed no significant difference in comet tail moment (TM) and tail scores and cytotoxicity up to 24 h respectively. In acute toxicity studies, oral administration of single doses of MERM (250-2,000 mg/kg) in Wistar rats produced neither mortality nor any noticeable changes in behavior. Hematological and biochemical parameters showed no difference, except for a significant increase in ALT and AST at the highest dose. Histopathological findings revealed hepatotoxicity and neurotoxicity at highest dose of extract. In subacute toxicity studies administration of MERM (1,000 mg/kg) for 28 consecutive days neither altered the body weight gain nor behavioral parameters. No significant change was observed in the hematological and biochemical parameters analyzed. Histopathological examination showed normal architecture suggesting no morphological disturbances. Collectively, these data demonstrate that consumption of MERM for various medicinal purpose is safe.