Cypermethrin is a synthetic pyrethroid, which is widely used against various agricultural, veterinary, horticultural and household pests. In the present investigation, an attempt was made to assess the acute toxic effect of sublethal concentration of Cypermethrin (25%EC) on the liver of Ophiocephalus striatus. The 96 hours LC₅₀ dose of Cypermethrin (25% EC) was found to be (0.72 ± 0.007µl lit ^-1). Liver was dissected out to observe the histopathological changes in the liver after exposure to Cypermethrin. Significant changes were noted in the liver. Study revealed the degeneration of the liver cells, hypervacuolation, pyknotic nuclei, loss and degeneration of connective tissues. Nuclear hyperplasia and hypertrophy was noted in the liver.