A retrospective study was conducted in 1216 cases to investigate the possible association between tobacco smoking and the risk of haematological malignancies. A small, but not significant, increase in malignancy was observed in smokers. Significant association was demonstrated between tobacco smoking and acute nonlymphoblastic leukaemia, and myelodysplastic syndromes. The duration and amount smoked increased the risk; heavy smokers presented significant positive associations with overall malignancies, acute nonlymphoblastic leukaemia, myelodysplastic syndromes, and monoclonal gammopathy of undetermined significance, whereas light smokers did not present any significant association. These data support a causal relationship between certain haematological malignancies and tobacco smoking. Further research is needed to examine the risk according to dose-response effect, and the variation in risk according to the histological subtype of the malignancy.