Sprague-Dawley rats were given 15, 70 and 140 min exposures to 15 mg/l 3,3-dimethyl-2-butanol, pinacolyl alcohol (PA), or 6-hour exposures to 0.2, 1.0 and 5.0 mg/l PA (1 mg/l = 240 ppm). A 50% mortality rate was obtained at the longest exposure to 15 mg/l. Sex related differences in the blood levels of PA and pinacolone were noted, and the surviving male rats failed to gain weight normally in the first week after exposure. In rats exposed to 5.0 mg/l for 6 hours, there were reductions in horizontal and vertical activity and the minute volume was 55% of controls at the end of exposure. Like many secondary alcohols, PA poses only a possible inhalation hazard; however, male rats may be somewhat more susceptible than females.