Cytoreductive surgery/heated intraperitoneal chemotherapy (CRS/HIPEC) has been shown to be effective for selected patients with advanced appendiceal cancer. We propose that delaying CRS/HIPEC leads to disease progression and affects outcome. A retrospective analysis of a prospective database was carried out. Patients were divided into two groups based on time from diagnosis to CRS/HIPEC (less than 6 months = early, greater than 6 months = delayed). Comparison was made of Peritoneal Cancer Index (PCI), Prior Surgery Score (PSS), complete cytoreduction (CC), and lymph node status. Overall survival (OS) was calculated using Kaplan-Meier estimates. Of 127 patients, 50 had disseminated peritoneal adenomucinosis and 77 had peritoneal mucinous carcinomatosis (PMCA). Of patients with PMCA, 41 had early CRS/HIPEC and 36 delayed. PCI was less than 20 in 46 and 17 per cent (P = 0.007) of the early and delayed groups, respectively. CC was achieved in 88 and 61 per cent (P = 0.009) of the early and delayed groups, respectively. PSS was (2 of 3) in 51 and 91 per cent (P = 0.001) of the early and delayed groups, respectively. Five-year OS was 54 per cent for the early group and 45 per cent for the delayed group (P = 0.2). Delaying CRS/HIPEC was associated with higher tumor load and lower chance for complete cytroreduction. Longer follow-up and larger numbers are needed to determine if OS difference will reach statistical significance.