Percutaneous penetration of [14C]parathion in mouse skin of nose, hind foot, scrotum, and tail was measured by recovery of excreted radioactivity relative to an intravenous dose. Oral ingestion was prevented by use of face muzzles and polyethylene rings at application sites. Penetration per unit area was in the following order (iv = 1.0): nose (0.8), scrotum (0.4), foot (0.3), and tail (0.3). Because of their greater surface area, tail and foot regions would contribute most to absorption in uniform ventral exposure. Daily recovery curves indicate apparent first‐order kinetics of elimination.