Unexplained elevation of serum IgE concentrations occurs in cigarette-smoking Caucasian males from temperate zones. To determine whether race or geography might be factors, we measured serum IgE concentrations in 94 Puerto Rican Hispanic patients, including smokers and nonsmokers. Mean serum IgE levels were elevated in our total patient population compared with Caucasian Americans. Geometric mean IgE was significantly increased in total smokers (157 IU/mL) compared with nonsmokers (78 IU/mL) and in male smokers greater than age 55 years (335 IU/mL) compared with male nonsmokers (41 IU/mL). Serum IgE was not significantly increased in female smokers. Among patients older than 55 years, persistent elevation of serum IgE occurred in male smokers. Our findings in a Puerto Rican Hispanic population are similar to those in studies of Caucasian smokers in temperate zones.