In recent years the Y-set with disinfectant [Buoncristiani et al. 1983] has been used in several continuous ambulatory peritoneal dialysis (CAPD) centers. This system has considerably improved the short- and long-term results of CAPD [Maiorca et al. 1983, Scalamogna et al. 1990]. Accidental introduction of disinfectant during the exchange is a risk associated with this system, but at the present time we have little data pertaining to incidence complication and its possible effects on peritoneal function. The aim of the present study was to assess the incidence of acute symptomatic accidental introduction of disinfectant in CAPD patients on the Y system and to establish whether this complication is followed by any long-term changes in peritoneal ultrafiltration.