• To determine the prevalence of blood eosinophilia in patients receiving maintenance peritoneal dialysis, routine peripheral WBC counts of 49 such patients were reviewed. In 29 patients, blood eosinophilia was noted. Elevations in blood eosinophil counts tended to be mild and episodic. They were often associated with concomitant elevation of peritoneal fluid eosinophil counts. Possible predisposing factors included recent peritoneal catheter insertion and antibiotic therapy for peritonitis.