Effects of nicotine administration on bone mineral density and calcium homeostasis were studied in male Sprague-Dawley rats. Rats aged three months, weighing between 200 – 250 g were divided into five groups, i.e. baseline, normal saline (control), nicotine 3 mg/kg, nicotine 5 mg/kg and nicotine 7 mg/kg. Treatment was given by intra-peritoneum injection, six days a week for eight weeks. Bone mineral density, bone calcium content as well as serum and urine calcium were assayed before and after treatment. The results showed that bone mineral density was increased in all the rats groups. Femoral bone calcium content was decreased in all the groups given nicotine compared to the normal saline control group. No significant effects of nicotine on calcium content of the fifth lumbar vertebra were seen. Serum calcium was lower in the group given nicotine 7 mg/kg after treatment compared to before treatment was started. However, no significant changes were seen in the urine calcium concentrations for all groups. Body weight was significantly lower in the group given nicotine 7 mg/kg compared to the control normal saline group at the end of treatment. In conclusion, treatment with nicotine 7 mg/kg for eight weeks impaired bone calcium content, calcium homeostasis and overall body growth.