The efficacy of recovery of peritonitis-causing microorganisms from peritoneal dialysate fluid by using the Septi-Chek blood culture system (Roche Diagnostics, Div. Hoffmann-La Roche Inc., Nutley, N.J.) was compared with those of other conventional techniques, such as the 20-ml culture and the filtration methods. The recovery of microorganisms by using the Septi-Chek system was found to be as effective as the filtration of 250 ml of dialysate that used a modified Millipore filtration technique (Millipore Corp., Bedford, Mass.). Both methods were found to be superior to the 20-ml culture method. We suggest using the Septi-Chek method as the standard protocol for the culture of dialysate as a relatively inexpensive and labor-saving recovery technique.