Two studies were conducted to examine the effects of prenatal alcohol exposure on ambulation and head-dipping behavior of rats. The apparatus was a modified "open field" that contained holes in the floor where an animal could "dip" its head. Animals were tested under conditions in which another animal was present in the adjacent box, or the adjacent box was empty. In the first study, 18-month-old rats, prenatally exposed to alcohol, ambulated more and made more head dips than controls when tested with an empty adjacent test box; when there was another animal in the adjacent box, animals prenatally exposed to alcohol did not differ from controls. In the second study, all rats were tested with the adjacent box empty. In this study, 8-month-old rats, prenatally exposed to alcohol, did not ambulate significantly more but did make significantly more head dips than controls. These results indicate that prenatal alcohol exposure has long-term effects on behavior and that some tests (head-dipping) are affected more reliably than others (ambulation). The results also suggest that test conditions may mask these differences.