This study investigated whether being on transdermal hormone replacement therapy (HRT) influenced smoking cessation variables in postmenopausal women undergoing short-term abstinence from cigarettes. Women were recruited into two groups according to their pre-enrollment medication status - currently on HRT (n = 17) or not on HRT (n = 13). The HRT group had their prior medication replaced with a standard 0.1 mg estradiol transdermal system and 2.5 mg of Cycrin daily. Following two weeks of medication adjustment, participants continued smoking as usual for one week, at which time baseline measurements were taken. For the remaining two weeks, participants were instructed to quit smoking. They were provided with smoking cessation counseling and monitored for abstinence. Data were collected during five clinic visits on all dependent measures: Minnesota Nicotine Withdrawal Scale, Beck Depression Inventory (BDI) Scale, Profile of Mood States, Motor Speed Tasks, and Reaction Time Test.