This paper describes invasion of an indwelling peritoneal catheter by a fungus. This colonization by Penicillium pinophilum, whose identity was proved by isolation, mycological characterization and in situ examination by scanning electron microscopy, did not cause peritonitis. We have discussed possible causes of contamination and implications of the findings. Fungi rarely are responsible for primary peritonitis in CAPD patients, though increasingly they are recognized as secondary agents (1). Mycetes so far isolated belong to the following genera: Aspergillus, Candida. Drechslera, Fusarium, Mucar, Rhodotorula and Trichosparan (2–10). Recently Pearson et al (II) described Penicillium peritonitis which appeared to have been induced by prolonged antibiotic therapy, following repeated episodes of bacterial peritonitis. A similar sequence was encountered after intestinal perforation (3). In CAPD patients peritonitis caused by fungi does not differ from the more common bacterial peritonitis (3), though at first the clinical symptoms may be attenuated and effluent solution may be clear (6, 11). In some cases however such peritonitis can be particularly severe and persistent (12). In these circumstances the catheter should ∼ removed (2, 13, 14), because then the infection clears without specific antifungal therapy. Colonization of the in -dwelling device is associated with a poor prognosis (15). This report describes a patient with massive colonization of the exposed tract of the Tenckhoff peritoneal catheter with Penicillium without clinical symptoms of peritonitis or changes in the dialysate effluent.