Hand and foot deformities were originally described in Parkinson's disease (PD) in 1864, although their pathogenesis still remains to be clarified. Typical hand deformities are flexion in metacarpopharyngeal joints and hyperextension in interphalangial joints, sometimes accompanied by ulnar deviation. Unlike rheumatoid arthritis (RA), there is no swelling and stiffness in joints. In this report, a case that was previously misdiagnosed as RA due to deformities in the hand and whose PD was detected upon presentation to our clinic is presented, and the differential diagnosis of the disease is discussed.