The effects of intraperitoneally administered formaldehyde (50000) on tissue glutathione (GSH) levels and bile production in male rats was evaluated. Labeled formaldehyde was administered at a dose level of 72mg/kg to male Sprague-Dawley-rats weighing 220 to 230 grams. Bile was collected from conscious, unrestrained animals 30 and 60 minutes prior to dosing, and at 30 minute intervals post exposure until predosing bile flow levels were achieved. Rats were sacrificed at designated time points to avoid unrelated alterations in GSH concentrations, and liver, kidney, lung, and brain tissue was excised. Mild cholinomimetic signs were noted within 30 minutes of formaldehyde administration, and disappeared after 4 hours. At 3 hours post dosing, significant decreases in GSH levels in liver, kidney, lung, and brain tissue were noticed. The liver presented with the greatest depletion of GSH, followed by the kidney, lung, and brain, with GSH levels of 39, 33, 31, and 22 percent of control, respectively. The rate of bile flow increased two fold within 2 hours of formaldehyde administration, but returned to normal levels within 5 hours. Maximum level of radioactivity excreted in the bile occurred at 2 hours and, after 6 hours, no significant radioactivity was noted. The authors conclude that GSH possibly plays a protective role in the toxicity of formaldehyde.