Monomelic amyotrophy is a rare clinical entity, resulting in wasting and we
akness localized to the hand and forearm unilaterally, in the absence of an
y sensory or long tract signs. The onset of the disease is insidious, occur
ring in males before the age of 30 years, with a clinical course marked by
non-progression, The case of a 19-year-old Indonesian male patient is prese
nted, with a one year history of right upper limb weakness. Nerve conductio
n studies were normal, without evidence of conduction block. Electromyograp
hy showed changes of chronic partial denervation. Magnetic resonance imagin
g scans revealed an asymmetry of the spinal cord. Possible aetiological mec
hanisms for these changes are discussed.