To investigate the reasons for the high mortality rate (65 percent 000) for Lung Cancer (LC) found in Rosario, Argentina, studies were carried out among patients with LC. Odds Ratios (OR) of different cell types associated with smoking habit and occupational hystory were quantified. The OR for the consumption of more than 40 cigarettes/day versus less than 20 cigarrettes/day was 11.6 for all LC (p<0.0001). OR associated with the use of unfiltered ciagarettes was 3.5 times higher than for filtered ciagarettes. The OR for smokers working at metallurgy plants was similar to Administrative Personnel (AP)and 2.3 times higher for Agriculture Workers (AG) (p<0.02); 3 times if AG worked more than 30 years and 5 times higher when squamous cell type was considered. Occupational contaminants could potentiate the risks of smoking habits favoring lung cancer.