Background Smoking is a major cause of cardiovascular disease and mortality. Smoking-related deaths in Greece account for 23%, whereas 41% of young Greeks are smokers, the highest percentage in Europe. The purpose of this study was to examine the effects of chronic smoking on the rate-pressure product and exercise tolerance in young, healthy male smokers. Design and methods Forty-two smokers and 51 nonsmokers were selected from a population of 543 students based on their age, sex, body mass index, physical fitness, smoking habit and health status. All participants were tested with the standard Bruce treadmill protocol. The rate-pressure product was obtained at rest and during exercise at a given submaximal workload. The evaluation of exercise tolerance was based on peak workload achieved and maximal exercise test duration. Results The smokers had a higher rate-pressure product at rest (P < 0.001) due to their higher resting heart rate (P< 0.001). Resting values of blood pressure did not differ significantly between the two groups. During exercise, smokers had a greater rate-pressure product (P< 0.001), mainly due to their significantly higher systolic blood pressure (P = 0.008). The smokers had a higher submaximal heart rate (P= 0.005), but the differences in heart rate between groups were reduced for smokers during exercise when compared to rest. The smokers’ exercise tolerance was impaired and their maximal exercise test duration time was significantly shorter (P< 0.001). Conclusions Chronic smoking was found to affect young male smokers’ cardiovascular fitness, impairing the economy and decreasing the capacity of their circulatory system. Eur J Cardiovasc Prev Rehabil 14:646–652 c 2007 The European Society of Cardiology