Peritoneal carcinomatosis has always been regarded as a contraindication in traditional cancer surgery treatment; however, good results have been reported by using new combined medical-surgical loco-regional techniques. Peritonectomy and chemohyperthermic perfusion with cisplatinum (CIIP) seem to play a central role in obtaining a better survival rate than with the traditional procedures, even though there is a cisplatinum nephrotoxic effect. The aim of this study was to investigate entity and type of renal injury after CIIP. Forty-two patients (12 males and 30 females) with recurrent or primary peritoneal carcinomatosis who underwent peritonectomy and cytoreductive surgery with hyperthermic intraperitoneal chemotherapy with cisplatin were enrolled. A significant worsening in renal function was observed on the third post-operative day and this condition then persisted for three months. A reduction in estimated-Glomerular Filtration Rate (e-GFR) and an alteration in the albumin:creatinine ratio proved tubular injury. On the third post-operative day after cisplatinum administration, a high toxicity peak was found following platinum free fraction excretion. Proximal tubular injury was confirmed even at the three month analysis. A significant correlation between the total protein reduction rate and the decrease in renal function was established. In relation to that, the platinum free fraction could increase because of a binding protein shortage and the nephrotoxic effect could be enhanced due to platinum accumulation within the post-operative period. This finding suggests that the higher the protein reduction is, the lower the e-GFR determination is at three months.