Effects of nicotine, nicotine+vitamin E and nicotine+Hippophea rhamnoides L. extract (HRe-1) on muscle, heart, lungs, testicle, kidney, stomach, brain and liver carbonic anhydrase (CA; EC 4.2.1.1.) enzyme activities were investigated in vivo. Groups of rats were given nicotine (0.5 mg/kg/day, i.p.), nicotine+vitamin E (75 mg/kg/day, i.g.), nicotine+HRe-1 (250 mg/kg/day, i.g.) and a control group vehicle only. The results showed that nicotine inhibited the heart, lung, stomach and liver CA enzyme activities by ∼80% (p < 0.001), ∼94% (p < 0.001), ∼47% (p < 0.001) and ∼81% (p < 0.001) respectively, and activated muscle and kidney, but had no effects on the testicle and brain CA activities. Nicotine+vitamin E inhibited the heart and liver CA enzyme activities by ∼50% (p < 0.001), and ∼50% (p < 0.001), respectively, and nicotine+vitamin E activated the muscle CA activity. However, nicotine+vitamin E had no effect on lung, testicle, kidney, stomach and brain CA activities. Nicotine+HRe-1 inhibited the heart and stomach CA enzyme activities by ∼51% (p < 0.001), and ∼32% (p < 0.002), respectively, and activated the muscle and brain CA activities, but had no effects on the lung, testicle, kidney, and liver CA activities. In vitro CA inhibition results for similar experiments correlated well with the in vivo experimental results in lungs, testicles, kidney, stomach, brain and liver tissues.