Background/Objective: To elucidate the correlation of Ki-67 with tumor biology and survival in appendiceal carcinoid tumors. Method: A retrospective chart review conducted on 51 patients with appendiceal carcinoid tumors who underwent surgical intervention from 1991 to 2008. MIB-1, an antibody of Ki-67, was used to determine cell proliferation and correlated with clinical and histological parameters. MIB-1 index was categorized according to the World Health Organization (WHO) classification. Result: Of the 51 patients, 32 had tumors <2 cm; 3 >2 cm; and 16 with unspecified tumor size. Increased MIB proliferative index did not significantly correlate with increasing tumor size (P = 0.426). Twelve patients had metastatic disease on presentation: 9 had MIB-1 index <2%, 1 had index 2-15% and 2 with index >15%. No significant correlation between MIB index and metastasis was demonstrated (P = 0.68). Median follow-up was 40 months (range 10-183 months) with a 51% follow-up rate. Seven mortalities and three recurrences presented in 26 patients. Assessment of survival demonstrated significantly decreased survival by increasing MIB index. Survival rate by MIB index was as follows: <2% was 97%, 2-15% was 85% and >15% was 67% (P = 0.02). Conclusion: Increased MIB index significantly correlated with decreased survival. No correlation was demonstrated by MIB index and tumor size or presentation with metastatic disease.