Two 37-year-old men, both drug addicts, and a 32-year-old homeless woman presented themselves with a painful arm. Except for the first patient, there was a delay in diagnosing the compartment syndrome of the arm. In the first patient emergency fasciotomy led to a good functional recovery, however kidney function was lost despite proper treatment, possibly due to combined heroine use and muscle breakdown. In the second patient prolonged immobility and altered consciousness by drug use should have increased clinical suspicion. Poor arm function remained even after fasciotomy. In the third patient inadequate clinical examination delayed surgery. Major early symptoms of compartment syndrome are progressive disproportional pain and sensory loss, not relieved by analgesia. If left untreated, the ischaemic tissue damage is potentially limb and even life threatening. The acute compartment syndrome is a clinical diagnosis and a low threshold for surgical exploration and fasciotomy is advocated.