Basophils are known to release histamine and to produce leukotrienes (LTs) following both IgE-dependent and -independent stimuli. Although there exist a few reports which examined the relationship between histamine release and LTs production, their conclusions were not always in agreement with each other. In the present study, we examined the relationship between histamine release and LTs production from basophils in the presence or absence of 1 ng/ml of interleukin-3 (IL-3). Normal basophils released a smaller amount of histamine and LTs than atopic determatitis (AD) basophils, when basophils were stimulated with an optimal concentration of anti-IgE antibody. When we examined the relationship of histamine release and LTs production from AD donors induced through Fc epsilon RI, we found a significant exponential correlation between these two mediators (R2 = 0.58 in the absence of IL-3, R2 = 0.83 in the presence of IL-3). Although IL-3 enhanced both histamine release and LTs production from AD donors, the relationship between these two mediators was not affected. In conclusion, there was an exponential correlation between histamine release and LTs production from AD basophils, which was not affected by the pretreatment with IL-3.