Most proximal femoral deformities encountered during hip arthroplasty are secondary to developmental processes, previous osteotomy, or fracture. A classification method is proposed in which deformities are categorized anatomically by level. Anatomic deformity levels include: greater trochanteric deformities, femoral neck deformities, metaphyseal level deformities, and diaphyseal level deformities. Deformities at each level may be angular, rotational or translational, abnormal bone size, or a combination thereof. Treatment is individualized according to patient needs and the anatomy of the deformity. Careful preoperative planning helps predict prosthesis requirements and technical challenges. If cemented implants are used, care must be taken to obtain reasonable alignment and a continuous cement mantle. For uncemented implants, obtaining a good fit is challenging and there is a risk of intraoperative fracture. Access to a wide range of implants helps the surgeon treat unique femoral geometries. Implants fixed in the diaphysis allow some proximal femoral deformities to be bypassed. Modular or custom implants simplify treatment of certain deformities. For patients with severe deformities, femoral osteotomy may be required. Successful osteotomy requires correcting the deformity, maintaining vascular supply of fragments, obtaining fixation of osteotomy fragments (with the implant or adjunctive fixation), and obtaining implant stability. Although most deformities can be treated during hip arthroplasty, occasionally there is a role for two-stage treatment: deformity correction followed later by arthroplasty.