Mangifera indica L. is a common horticulture and medicinal plant, which is used traditionally to treat various infections. A previous study has shown its leaf extracts to have antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. This study investigated the activity of the leaf extracts against Clostridium tetani, which causes many deaths around the world. Ether and ethanolic leaf extracts were obtained by sequential extractions. Qualitative studies were carried out to determine the different classes of compounds in the extracts. The chemical tests showed that the ether extract had saponins, steroids and triterpenoids, while the ethanol extract had alkaloids, anthracenosides, coumarins, flavonones, reducing sugars, catechol and gallic tannins, saponins, steroids and triterpenoids. The minimum inhibitory concentration (MIC) of the extracts against the study organism was determined using the gradient serial dilution method. Gentamycin and distilled water were used as controls. Both the ethereal and ethanolic fractions showed anti-clostridium tetani activity with an MIC of 6.25 and 12.5 mg ml−1, respectively.