Interferon gamma (IFN-gamma) exerts major pro-inflammatory, regulatory, and anti-inflammatory actions in immune defense responses. In asthma the infiltration of eosinophils, neutrophils, and lymphocytes is a critical event. Chemokines stimulate the migration of the susceptible subset of inflammatory cells. The chemokine receptors CCR-3 are mainly expressed in eosinophils, basophils, and Th2 cells. More recently it has been demonstrated that the IFN-gamma downregulates the expression of some chemokine receptors. IgE determinations were performed using an ELISA for total IgE Peripheral blood leukocytes from patients and controls were isolated by Ficoll-Hypaque gradient. The cells were incubated in the absence or presence of 500 IU/ml of recombinant human IFN-gamma for different times. After incubation the cells were washed and lyzed for reverse transcription-polymerase chain reaction (RT-PCR) analysis. RT-PCR was performed using a Perkin-Elmer kit. The amplified bands were run in 2% agarose gels and quantified. The basal levels of CCR-3 in asthmatic patients with IgE > 150 IU/ml tend to be higher than in controls. IFN-gamma down-regulates the expression of CCR-3 in peripheral blood leukocytes from asthmatics with IgE >150 IU/ml, when compared with the basal levels of expression. In conclusions, through the modification of the expression of CCR-3 in peripheral blood leukocytes from atopic asthmatics, IFN-gamma could exert a beneficial effect in patients with asthma, regulating the migration of some inflammatory cells involved in the pathogenesis of the disease.