Propoxur (Baygon, 2-isopropoxyphenyl N-methylcarbamate) is a carbamate pesticide commonly used against house insects. When the insecticide was administered intramuscularly in rats it was converted to a new metabolite which was found to be present in the serum, liver, kidney and brain 6 h after the administration of the pesticide. The metabolite was purified by high performance liquid to chromatography and comparison of the infrared spectra of Propoxur and the metabolite showed that a deamination reaction was responsible for the formation of the metabolite from the parent pesticide. The pesticide also induced haematological changes such as an increased level of total bilubrin, amylase and glutamic-oxalacetic transaminase and decrease of cholinesterase activity, indicating damage of the liver and nervous system in rats.