Expeditious diagnosis of peritonitis remains a significant goal in the management of patients maintained on peritoneal dialysis. Several attempts to use leukocyte esterase reagent strips to diagnose peritonitis have been described. In this study we examined the usefulness of a new reagent strip, the PeriScreen Test Strip, in the diagnosis of peritonitis. A series of 72 peritoneal effluent samples obtained from 22 maintenance peritoneal dialysis patients is reported. In this study, the test strips had a sensitivity of 100% and a specificity of 98.3% as compared to an abnormal leukocyte count. Thus, in the diagnosis of peritonitis we believe that the PeriScreen Test Strip can be used as a simple bedside screening test to exclude peritonitis in peritoneal dialysis patients.