In a previous subchronic inhalation toxicity study (HLR 129-88), diethylene glycol dimethyl ether (diglyme) produced testicular injury and degeneration of germinal cells in the epididymides of rats at concentrations of 110, 370 or 1100 ppm. To determine a no-observable-effect level for the testicular injury, 4 groups of 20 male Cr1:CD*BR rats were exposed nose-only, 6 hours/day, 5 days/week for 2 weeks to diglyme at concentrations of 3.1, 9.9, 30, or 98 ppm. A procedural control group of 20 male Crl:CD*BR rats was exposed to air only. After the 10th exposure, 10 rats per group were killed for gross examination. Selected tissues of the male reproductive system were weighed and processed for histomorphologic examination. The remaining rats were killed after a 14-day recovery period and subjected to the same gross and microscopic examinations.