The methodology used and preliminary results of a study examining the effects of perinatal methanol (67561) exposure in rats were described. Four groups of 12 pregnant Long-Evans-rats each were exposed whole body to methanol vapor at a nominal concentration of 4,500 parts per million (ppm) 6 hours daily beginning on day 6 of gestation. The exposures were carried out in hexagonal 2 cubic meter 'Rochester' chambers. The mean methanol concentrations in the chambers, determined by Miran 1A infrared spectrophotometers, were 4352, 4282, 4582, and 4471ppm. Exposure continued through gestation, delivery, and up to postnatal day (PND) 21. One group of pups was exposed to PND 52. Control animals were exposed to filtered air. No exposure related effects on dam and pup weight gains and pup litter size and sex distribution were observed. Measurements of blood methanol concentrations indicated that maternal blood methanol concentrations remained fairly constant during gestation and lactation, the mean concentrations during these periods being 0.55 and 0.56mg/ml, respectively. Pup blood methanol concentrations measured just before weaning averaged 1.26mg/ml. Pup blood methanol concentrations in the group maintained to PND 52 decreased over time until PND 48 at which time they were comparable to those of the dams. Light microscopic examination of the brains of exposed pups on PNDs 1 and 21 showed no neuropathological changes; however, expression of neural adhesion molecules having molecular weights of 140 and 180 kilodaltons in the cerebellum were significantly decreased compared to the controls. This difference was not seen in animals examined 15 months later. The implications of these results for assessing the risk to the general population if methanol were to be adopted as an automobile fuel were discussed.