Nicotine chewing gum (Nicorette 4 mg) and an identical placebo gum were administered on different days, in a double-blind cross over fashion, to 4 men, aged 25-52 years, and 4 women, aged 21-49 years, all healthy non-smokers. The subjects chewed the gum for 30 min and heart rate, blood pressure, electrocardiogram, finger tip temperature, calf and hand blood flow and whole blood nicotine levels were measured for 240 min in the supine position, under indirect body heating. 72% -96% of the nicotine was absorbed. Only heart rate showed a significant increase (10%-12%) during the study as compared to placebo. The mean peak nicotine level was 6.5 ng/ml, which occurred at 15-60 min and roughly coincided with the peak heart rate, and then levelled off to around 3 ng/l at 120-240 min. All subjects complained of nausea, dizziness or anxiety to varying degrees. It is concluded that if healthy non-smokers chew Nicorette gum 4 mg by mistake, they would probably suffer more from generally unpleasant symptoms than from any cardiovascular upset.