The rambutan (Nephelium lappaceum L.) peel extract has been reported to contain fermentation inhibitor components that inhibited alcoholic fermentation in cider and cassava tapai. This research was aimed to investigate the rambutan peel and its extract as a potential fermentation inhibitor to delay alcoholic fermentation in sugar palm sap for alcohol production. The rambutan peel used in this research was semi-dried peel with concentrations of 35, 40 and 45% and ethyl acetic peel extract with concentrations of 0.4, 0.8 and 1.2%. Both semi-dried and extract were applied to sugar palm sap and observed for seven days. Physicochemical properties (pH, total dissolved solid, total reducing sugar, total titratable acidity and alcohol content) and microbiological enumeration were observed. Semi-dried peel was able to delay alcohol production in sugar palm sap for one day compared to the control. On the other hand, ethyl acetatic peel extract was able to significantly delay the alcohol production in sugar palm sap. After seven days, the alcohol content of saps added with 0.4% and 0.8% of rambutan peel extract were 2.95±0.04% and 0.17±0.04%, respectively, as compared to the control with 5.41±0.41% of alcohol. Moreover, ethyl acetic peel extract with concentration of 1.2% was able to completely delay fermentation and resulted in sugar palm sap with no alcohol content after seven days. Palm saps with high alcohol content from each treatment were distilled into ethanol. The bioethanol produced had alcohol concentration of 38-46%. The best treatment to produce bioethanol was 0.4% of ethyl acetate extract on day 7 as it had the highest alcohol yield.