Acrawax is a trademark for a series of synthetic waxes which are used as flatteners in paint, and lubricants in plastics, and these materials have been routinely regarded as nuisance dusts. Due to a paucity of information regarding the pulmonary toxicity of this material, we investigated the effects of acute inhalation of Acrawax C in rats. CD rats were exposed to aerosols of Acrawax C for 6 hours at 112 mg/m3. Fluids and cells from sham and exposed animals were recovered by bronchoalveolar lavage (BAL) and measured for cellular and biochemical parameters at 0, 24, 48, 172 hrs (8 days), and 1 month postexposure. Pulmonary macrophages (PM) were cultured and studied for in vitro and in vivo phagocytosis, as well as surface morphology. The lungs of additional animals exposed to Acrawax were fixed for assessment by histopathology, and transmission electron microscopy. Our results showed that Acrawax C exposure produced a mild inflammatory response at 24 hours postexposure, but cell differentials were not significantly different from controls at 48 hrs after exposure. BAL levels of lactate dehydrogenase, alkaline phosphatase and protein were slightly different from controls only at 8 days postexposure, and had returned to control values by 1 month of recovery. Acrawax exposure had no adverse effects on either morphology or the phagocytic capacity of pulmonary macrophages recovered from exposed animals. Histopathologic analysis of lung tissue from Acrawax C-exposed rats revealed normal lung architecture. Based on acute studies, our results suggest that the response to inhaled Acrawax C is not substantially different from the response to other nuisance dusts such as carbonyl iron and titanium dioxide.