Osteochondrosis of the primary ossification centre of the patella (Köhler’s disease) has been reported as a rare cause of anterior knee pain in children between 5 and 9 years of age. The aetiology remains unclear. This is the first case report presenting a late bilateral patellar osteochondrosis with unilateral involvement of the proximal pole in an 11-year old boy with documented growth retardation. This case highlights the importance to thoroughly investigate young patients with patellar osteochondrosis for growth retardation. This case might indicate that growth retardation rather than growth spurt is an important aetiological factor of osteochondrosis.