Paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) has in the last decade gained popularity as an effective weedicide. It is marketed for commercial use as a liquid concentrate Gramoxone ICI (20% paraquat). Accidental or intentional ingestion of Gramoxone has caused 232 human deaths between 1964 and 1973 (Anon 1974). Most human patients suffer transient renal and hepatic insufficiency and pulmonary oedema followed after a latent period by progressive pulmonary fibrosis leading to death from respiratory failure (Harrison 1972). The clinical features of non-fatal paraquet poisoning in a cat and the clinical and pathological findings in fatal poisoning in a dog are reported.