Lead was determined in whole blood samples obtained from 161 Saudi male volunteers. The influence of smoking on lead exposure was investigated. Blood lead was significantly higher in smokers than in non-smokers (p < 0.05). The association between blood lead concentrations and lymphocytes subsets was examined. Among the measured immune variables only helper inducer cells, helper suppression ratio and T suppressor-inducer cells showed a significant relationship with blood lead. However, in both cases, this effect was not seen when the non-smoker group was examined. In this study smoking, which constitutes an important source of lead exposure, can alter the immune response.