In the present study the migratory function of eosinophil and neutrophil granulocytes from patients with asthma were investigated. Fifty-seven patients with asthmatic disease of varying severity were included. Eosinophil and neutrophil chemotactic responses to 5% pooled normal human serum (NHS), 5% allergen-challenge serum, 2.5% zymosan-activated serum, N-formyl-methionyl-leucyl-phenylalanine (10 nmol/L), chemokinetic responses to albumin (2 gm/L) and 5% NHS, and the eosinophil and neutrophil chemotactic and chemokinetic activities of serum were investigated. Eosinophils from patients with asthma demonstrated significantly (p less than 0.02) increased chemotactic responses to allergen-challenge serum, zymosan-activated serum, and N-formyl-methionyl-leucyl-phenylalanine, compared with eosinophils from references. The chemokinetic responses to albumin and NHS were increased (p less than 0.01) by eosinophils from the patients who had blood eosinophilia (greater than 400 X 10(6)/L). Sera from the patients with asthma demonstrated raised eosinophil chemotactic activity (p less than 0.001) and raised eosinophil and neutrophil chemokinetic activity (p less than 0.001). The eosinophil chemokinetic activity of serum was correlated to the relative peak expiratory flow rate of the patients (r = -0.43; p less than 0.02). The increased migratory responses were specific for the eosinophils, since the migratory responses of their neutrophils were not altered compared with that of the references. These results suggest that the eosinophils from the patients with asthma had been exposed to a priming mechanism in vivo.