In a group of 34 industrial workers, chronically exposed to organophosphorus (OP) compounds, serum pseudocholinesterase activity was depressed significantly in the exposed group as compared to the control group. There was a significantly higher incidence of peripheral neuropathy among the workers exposed to OP compounds, as compared to the control group. Mild to profound sensorineural hearing deficits were detected in both the exposed and control groups. As the pre-exposure hearing status of the workers was not known and since many other factors can also cause pathological changes in the cochlear nerve, a definite conclusion about the ototoxic nature of the OP compounds could not be drawn.