In a prospective cohort study of more than 330,000 Swedish construction workers, we explored the effect of tobacco smoking, oral moist snuff use, and body mass index (BMI) on the risk of developing leukemia (excluding chronic lymphocytic leukemia) and multiple myeloma (MM). Study subjects were participants of a health surveillance system within the building industry. Record linkage to the nationwide Swedish cancer registry, migration registry, and cause of death registry made a comprehensive follow-up available. A total of 372 incident cases of leukemia and 520 subjects with MM was ascertained. An increase in risk of acute myelogenous leukemia (AML) was observed in current smokers (incidence rate ratio, 1.50; 95% confidence interval, 1.06-2.11). Furthermore, there was an indication of a possible association between smoking intensity and risk of acute lymphocytic leukemia. Results on snuff use as well as BMI showed no association. This study confirms the role of smoking as a risk factor for AML and gives no support to the hypothesis of a role of snuff use or BMI level on the risk of leukemia or MM.