A study was carried out to determine the effect of 1-MCP applied to intact tomatoes differing in maturity stage on quality of stored tomato slices. 1-MCP (1 mL L-1, 20 °C, 12 h) was applied directly to intact tomatoes from ‘turning’, ‘pink’, and ‘light-red’ stages of maturity. After slicing, slices were stored for up to 10 days at 5 oC. 1-MCP maintained slice quality during storage following treatment of intact ‘turning’ and ‘pink’ maturity fruit as indicated by higher titratable acidity, higher ascorbic acid concentration, and lower lycopene content.1-MCP treatment did not significantly affect soluble solids and electrolyte leakage. Slices from ‘light-red’ maturity stage fruit did not respond to 1-MCP. The results show that application of 1-MCP to intact tomatoes was effective in maintaining tomato slice quality if 1-MCP is applied to fruit at early (‘turning’ and ‘pink’) stages of maturity. Keywords: 1-methylcyclopropene, soluble solids, acidity, ascorbic acid, lycopene, electrolyte leakage - Pangaribuan, Darwin Habinsaran; (Editor in Chief) Bogor Agricultural University, Indonesia