Although clinical evidence suggests a causal relationship between arch structure and musculoskeletal injury patterns, biological variations in soft-tissue structures effect the accuracy of arch-height measurements. Medial longitudinal arch (MLA) structure was assessed clinically and radiographically in 100 consecutive patients with foot problems. Intraclass correlation coefficients were calculated for three radiographic parameters and three anthropometric parameters of the MLA. Intrarater and interrater reliability estimates for the radiographic measurements were uniformly excellent. Intrarater reliability coefficients were higher than interrater coefficients for the three tested anthropometric parameters. The strengths of associations between anthropometric and radiographic data were assessed with Pearson correlation coefficients. The clinically determined ratio of navicular height-to-foot length correlated most closely with the radiographic indices of MLA structure.