B ackground: Extracts containing flavonoid compounds are often used in an effortto increase the antibacterial properties of dental materials. One example is the useof ethanolic extract of propolis (EEP). Glass ionomer cement (GIC) modified withEEP has been proven to improve antibacterial properties, but this modification issuspected to compromise their compressive strength. Objective: To determine theeffect of adding ethanolic extract of propolis from Trigona spp. on the compressivestrength of GIC. Methods: The research type conducted was laboratoryexperiment. Twenty cylindrical GIC samples measuring 6 mm (height) x 4 mm(diameter) were divided into 4 groups according to the proportion of propolis addedto the GIC liquid. A: conventional GIC (control), B: GIC modified with EEP at25% w/w, C: GIC modified with EEP at 30% w/w, and D: GIC modified with EEPat 35% w/w. After the samples were immersed in artificial saliva and incubated at37°C for 24 hours, universal testing machine was used to test the compressivestrength of the samples. Data collected were analysed with one-way ANOVA andTukey’s test (p<0.05). Results: The addition of EEP decreased the compressivestrength of the GIC liner. An insignificant decrease was observed when 25% EEPwas added (p>0.05). On the contrary, 30% EEP and 35% EEP resulted in asignificant decrease in compressive strength (p<0.05). Conclusion: EEP added ina proportion of 25% w/w does not significantly affect the compressive strength ofGIC. Thus, its use as a liner material can be considered.