In rats, effects of nicotine administration on sensory gating as indexed by prepulse inhibition (PPI) of the acoustic startle reflex (ASR) are unclear. We have found that nicotine administration enhances ASR and PPI in Sprague-Dawley rats, but other investigators, using Long-Evans rats, have reported no effects or enhancement of PPI only. Numerous methodological differences exist among studies in addition to subject strain, however, making it unclear whether inconsistent behavioral responses are the result of different experimental procedures or indicate a true strain difference. To investigate the role of strain in nicotine's effects on ASR and PPI, 192 male and female Long-Evans rats were administered 12 mg/kg/day nicotine via osmotic minipump for 14 days using identical methodologies employed in studies with Sprague-Dawley subjects. Effects of grouped vs. individual housing on these responses also were examined. Nicotine administration impaired ASR and PPI in Long-Evans subjects. These effects occurred in female rats regardless of housing condition, and interacted with housing in male rats. Results indicate that sex and housing are important variables in nicotine's effects. Results suggest that subject strain may be an important variable in nicotine's effects on sensory gating, and that responses of Sprague-Dawley vs. Long-Evans rats may represent a true strain difference.