The present series of experiments were conducted to discover whether rats would self-administer acetaldehyde (AcH) intravenously. The first study establishes the basic parameters for AcH self-injection in rats at 80% reduced body weight on a fixed-time 1 min (FT-1) food delivery schedule tested in the dark phase of a 12:12 light/dark cycle. The results show a dose-dependent effect with 1.3% AcH being the preferred dose as measured by the number of infusions. In the second experiment rats were on 100% free-feeding and at 80% reduced body weight, both conditions either with or without the influence of a FT-1 min schedule. The findings indicate that an interaction between dose, food deprivation and a FT-1 min schedule appears to initiate and maintain high levels of AcH self-injection in the dark. In a further experiment using 1.3% AcH the self-injection rates of animals at 80% body weight with a FT-1 min schedule reveal that the time of day of testing may be an important variable for inducing AcH intake. The results suggest that under altered environmental conditions AcH may have both an aversive and reinforcing effect.