Aim: To isolate the spermicidal constituents of Sacoglottis gabonensis. Materials and methods: The ethanolic extract with partitioned fractions of Sacoglottis gabonensis stem bark were subjected to sperm immobilization assay. The most active EtOAc fraction was further purifi ed by column and Semi-Preparative High Performance Liquid Chromatography to give compounds which were characterized by spectroscopic methods (UV, LC/MS, and NMR). The compound(s) was also tested for sperm immobilization activity. Results: The ethanolic extract showed 100% signifi cant (p < 0.05) sperm immobilization activity at a concentration of 30 mg/mL at 20 s compared to both negative and positive controls. The most active ethyl acetate fraction yielded methyl 3,5-dihydroxy-4-methoxybenzoate, eriodictyol and bergenin. Bergenin had 100% sperm immobilization activity at 20 mg/mL in 60 s which was signifi cant (p < 0.05) also when compared to the positive and negative control while methyl 3,5-dihydroxy- 4-methoxybenzoate, eriodictyol were not active. Conclusion: The active spermicidal constituent in Sacoglottis gabonensis stem bark extract is bergenin. However, methyl 3,5-dihydroxy-4-methoxybenzoate and eriodictyol showed no activity. This plant is known for its aphrodisiac action; hence, caution may have to be exercised in its use because of its spermicidal eff ect.