This study was designed to determine the usefulness of magnetic resonance imaging (MRI) in managing congenital hip dysplasia and dislocation. We compared various hip parameters using bony and cartilaginous landmarks. MRI determined that the bony acetabular index (AI) accurately reflects the cartilaginous AI. Bony acetabular indices greater than 30 degrees indicated hip dysplasia, subluxation, or dislocation. MRI demonstrates qualitative information not available on plain films; however, it does not provide further quantitative data, so we do not recommend its routine use in the evaluation of congenital hip dysplasia. The true benefit of MRI may be its ability to identify a group of patients with bone dysplasia but normal cartilaginous growth potential.