Chronic disseminated candidiasis (CDC) is a form of Candida species infection observed primarily in patients with acute leukemia. To investigate possible genetic factors associated with CDC, we conducted a pilot study of 40 patients with both leukemia and CDC and 50 control patients with leukemia only. A common haplotype of the IL4 promoter (-1098T/-589C/-33C) was overrepresented in patients with CDC (P= .01; odds ratio [OR], 2.16), whereas another common haplotype (-1098T/-589T/-33T) appeared to be protective against CDC (P= .018; OR, 0.47). Genetic variants of IL4 could contribute to the development of CDC in patients with acute leukemia.