Denture base made of heat-cured acrylic resin can be sometimes fractured easily during impact such as falling while cleaning it. This study aimed to evaluate the impact strength of heat-cured acrylic resin added with banana (Musa acuminata Linn.) stem fiber of 0.5%, 1%, 1.5% by weight. A total of 32 plate-shaped specimens of heat-cured acrylic resin measuring 65 x 10 x 2.5 mm were divided into 4 groups, group I as control (without addition of banana stem fiber), group II (with addition of 0.5% banana stem fiber), group III (with addition of 1% banana stem fiber), and group IV (with addition of 1.5% banana stem fiber), then the impact strength test was performed using a Charpy Impact Tester. The result shows that the impact strength were increased from group I to group IV and the data obtained were analyzed statistically using One Way ANOVA and post hoc LSD test (p <0.05). The data showed significantly results of the impact strength value with group IV as the highest among all groups, and an increase in impact strength occurred along with increase in the percentage of fiber added to the heat-cured acrylic resin. Based on the results, banana stem fiber has the potential as heat cured acrylic resin reinforcement materials.