Kimura's disease is known as a rare chronic inflammatory disease occurring mainly in the head and neck regions of Asian male patients. We present a case of Kimura's disease with extensive involvement of the bilateral upper extremities in a 20-year-old Korean man. Ultrasonography (US) and magnetic resonance imaging (MRI) demonstrated the presence of partially ill-defined, conglomerated soft tissue masses centered in the subcutaneous layer of both upper arms, with cranial extension along the cutaneous nerve in the right lesion. Medial epitrochlear, axillary and lower cervical lymphadenopathy accompanied the masses.