As the average age of society increases, identifying and preventing osteoporosis becomes more important. According to the results of the Women's Health Initiative study, substitution of estradiol is not recommended in hormone replacement therapy (HRT), although phytoestrogens might be a safe alternative. In this study, the osteoprotective effects of genistein (Gen), resveratrol (Res) and 8-prenylnaringenin (8PN) were evaluated by analysing bone biomechanical strength and bone mineral density. After ovariectomy, 88 female rats received soy-free food (C), and according to their grouping, were fed estradiol (E), GEN, RES or 8PN for 12 weeks. The phytohormones were given in two dosages. To analyse the osteoprotective effects of the tested substances, bone biomechanical properties and bone mineral density (BMD) were evaluated on the upper tibial metaphysis. Bone biomechanical properties were significantly improved after treatment with E (F (max): 90.6 N) and 8PN (85.0 N) compared to GEN (76.0 N), RES (72.6 N) and C (76.6 N). Bone biomechanical properties with 8PN (yL: 55.7 N) supplementation reached a level similar to that seen after E (49.3 N) supplementation. Treatment with GEN (38.5 N) was not as effective as E and 8PN, but demonstrated improved biomechanical properties compared to C (40.1 N) and RES (36.3 N). E (Cn.Dn. 217 mg/cm (3)) and 8PN (165 mg/cm3) showed superior results in the analysis of bone mineral density compared to C (112 mg/cm (3)). GEN (164 mg/cm (3)) also demonstrated superior results, though not as good as E and 8PN. RES (124 mg/cm (3)) revealed no effect on bone density. Treatment with 8PN resulted in very good biomechanical properties and showed an increased BMD. GEN had a smaller effect on bone biomechanical strength, while RES did not have an effect on bone biomechanical strength or BMD. Therefore, 8PN might be a safe alternative for HRT, but further studies are needed.