Background/Aims: The role of dietary protein in bone health is controversial. The objective of the present study was to examine the association between protein intake, dietary calcium, and bone structure measured by broadband ultrasound attenuation (BUA). Methods: Our analysis includes 8,178 female study participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) Potsdam Study. Ultrasound bone measurements were performed on the right os calcis, and BUA was determined. Dietary intake was assessed by a standardized food frequency questionnaire. We applied linear regression models to estimate the association between dietary protein and BUA. Results: After multivariate adjustment, high intake of animal protein was associated with decreased BUA values (β = –0.03; p = 0.010) whereas high vegetable protein intake was related to an increased BUA (β = 0.11; p = 0.007). The effect of dietary animal protein on BUA was modified by calcium intake. Conclusion: High consumption of protein from animal origin may be unfavourable, whereas a higher vegetable protein intake may be beneficial for bone health. Our results strengthen the hypothesis that high calcium intake combined with adequate protein intake based on a high ratio of vegetable to animal protein may be protective against osteoporosis.