Although previously reported in the literature, the existence of chemical peritonitis due to vancomycin in patients on peritoneal dialysis remains controversial. We report four similar episodes of sterile peritonitis in three patients receiving intraperitoneal (IP) vancomycin. The prior report implicated a change in the brand of vancomycin preparation, from Vancocin to Vancoled, as a contributing factor. We noted the occurrence of such episodes following a switch from Vancocin to a generic preparation from Abbott Laboratories. High-performance liquid chromatographic (HPLC) profiles of the three preparations show Vancocin to have a lower level of impurities than the other two; the presence of certain contaminants in the other brands may be contributing to the clinical difference observed. We conclude that chemical peritonitis due to IP vancomycin administration does occur, and that increased awareness of this entity could allow other cases to be identified.