Biomedical engineering serves as a solution for multiple biological problems through its application of scientific methods to address medical challenges. The biomedical field uses artificial bone and dental implants as examples of engineering applications that fall under this category. Medical scenarios require hip joint implants for patients who need bone replacement due to arthritis. The number of patients with arthritis who need artificial hip implants continues to rise because these implants have become more widely accepted for treatment. The artificial hip implant serves as a crucial element that maintains initial stability when implant failure occurs. The research investigates how different femoral head diameters affect stress distribution in complete hip replacement implants. The research used SolidWorks Premium 2025 to create seven hip implant models with Ti-6Al-4V alloy biomaterials and different femoral head diameters from 28mm to 52mm. The implants underwent finite element analysis through ANSYS 2022 R-2 to determine their Von Mises Stresses. The research findings show that Von Mises Stresses decrease when femoral head diameters increase. The 28mm femoral head diameter produced the highest Von Mises stress of 242.16 MPa, but the 52mm diameter produced the lowest stress of 180.87 MPa. The research findings will enable future studies about how different femoral head diameters affect hip prosthesis implant stress distribution.