Information is limited on blood nicotine levels among laboratory animals subjected to smoking or nicotine injections. This study was done to provide such information on blood nicotine levels in hamsters to better investigate nicotine-related pathology, using levels similar to those of human smokers. Blood nicotine levels were quantitated by gas chromatography and mass spectrophotometry among adult hamsters smoking one of three different strength cigarettes and hamsters injected with four different doses of subcutaneous nicotine, and their controls. The recorded levels rose dose dependently with increasing cigarette strengths and increasing doses of injected nicotine. Based upon regression equations, blood nicotine levels in the hamster model approximating human habitual ad lib. smoking are achieved by using a 1.56-mg nicotine cigarette or injecting 0.15 mg/kg nicotine. The Syrian golden hamster provides a good model for acute or chronic studies involving cigarette smoking.