The effects of a single inhalation exposure in the rat to the saturated vapors derived from four ethylene glycol monoalkyl ethers have been investigated. No effects on the test is observed following exposure to ethylene glycol isopropyl ether (EG ISOPE) and ethylene glycol butyl ether (EGBE), but there were marked reductions in testicular weight 14 days after exposure to EGME and ethylene glycol monoethyl ether (EGEE). Further studies were designed to establish the effect of a single exposure to EGME. Mature male albino rats were exposed to various levels of EGME vapor for a single 4 hour period and killed 14 days later. Following this single exposure a dose-related decrease in testis weight was observed in rats exposed to 5000, 2500 or 1250ppm EGME. Histopathological examination revealed disordered spermatogenesis and tubular atrophy in these animals. Minimal degenerative changes were seen in the testis of rats exposed to 625ppm EGME. When rats were examined at various time intervals after exposure to EGME vapor for 4 hours testis weight was reduced in rats examined 2 days after exposure to 2500 and 1000ppm EGME and remained depressed when compared to control values for up to 19 days following exposure. Histopathological examination of the testis revealed disordered spermatogenesis in exposed animals evident at 1 day following exposure to either 2500 or 1000ppm EGME.