Purpose: To evaluate the results after a cementless total hip arthroplasty using a cone prosthesis in dysplastic or deformed femurs. Materials and Methods: Twenty six patients (28 hips) with a dysplastic or deformed femur were evaluated after a primary total hip arthroplasty using a cone prosthesis. The average age at surgery was 42 years. The average followup duration was 6.2 years. The Harris hip scores, clinical and radiological results were evaluated. Results: The mean Harris hip score increased from 60 points preoperatively to 88 at the most recent follow-up. All the hips had a press fit at both the proximal canal and isthmus level. osseointegration was observed in 26 cases (93%) on the latest follow-up radiograph. The radiolucent line around the femoral stem was observed in 8 cases (29%). No stem showed significant subsidence. Femoral osteolysis developed in 5 cases (18%), which were limited to Gruen zones 1 and 7. Four femurs (14%) were revised; 3 femurs (11%) for excessive wear of the polyethylene liner and osteolysis, and 1 femur (4%) with stem loosening . Conclusion: A cone prosthesis is suitable for patients with dysplastic or deformed femur because it can correct anteversion for a deformed or dysplastic femur, achieve initial stability with a press fit, and obtain secondary stability through osseointegration .