A case of a 23 year old female with peritoneal melanosis associated with adenocarcinoma of the rectum is reported. During laparoscopic anterior resection of the rectum, diffuse black pigmentations on the parietal peritoneum, greater omentum, mesenteric lymph nodes and ovaries were discovered. The histopathological findings revealed the presence of macrophages packed with black pigment. These results together with clinical data excluded metastatic melanoma and confirmed the diagnosis of the rare condition called peritoneal melanosis. Due to the benign character of the lesions the laparoscopic treatment was continued. There were no remissions or progression of the peritoneal lesions observed. There have only been 14 cases of peritoneal melanosis reported in English literature and this is the second case of peritoneal melanosis that has been associated with adenocarcinoma of the large intestine.