Since April 2010, combination therapy consisting of peritoneal dialysis and hemodialysis (PD+HD) can be calculated as a medical service covered by the Japanese National Health Insurance. Prior to April 2010, billing for medical service fees was confusing and hindered the widespread adoption of PD+HD combination therapy. Therefore, the EARTH (Evaluation on the Adequacy of Renal Replacement Therapy) Study Group conducted a questionnaire survey to investigate the actual state of affairs with regard to billing for medical service fees related to PD+HD combination therapy. A questionnaire survey was conducted between August 2009 and September 2009 at 30 facilities by the EARTH Study Group. PD+HD combination therapy had been performed at 29 of these facilities. During this 1-month period, 1,267 patients underwent PD, and 281 of these patients underwent PD+HD combination therapy. The following items included in the insurance billings for these patients were reviewed : management fees for continuous ambulatory peritoneal dialysis (PD management fees), PD material costs, outpatient medical management fees for chronic maintenance dialysis patients (medical management fees), HD material costs, and HD procedure fees. The actual situation regarding billing for these items was determined at only 16 facilities that responded that they were performing PD and HD as combination therapy within their own facility. The results showed that PD material costs were billed at all 16 facilities and PD management fees were billed at all 16 facilities except one. Medical management fees were billed at 6 facilities (37.5%). HD material costs were billed at 14 facilities (87.5%), but were not billed at the other 2 facilities. HD procedure fees were billed at only 2 facilities (12.5%). The results for the insurance billing at 13 facilities that responded that they had asked another facility to perform HD showed that there were 15 different patterns of billing for PD performed at the facility itself and HD performed at the other facility. Prescription drug fees or specific health insurance fees for medical materials can be calculated for PD+HD combination therapy according to the insurance calculation rules. Furthermore, this can be done in cases in which HD and PD are performed at different sites. However, only 3 (23.1%) of the 13 facilities interpreted the rule as such to claim the medical fees. This survey showed that there is a great deal of confusion at clinical sites with regard to the billing rules for PD+HD combination therapy.