Background: Hoffmann's syndrome is a rare form of hypothyroid myopathy. Only a few cases of fasciotomy in this setting have previously been reported. Case presentation: A 41-year-old Caucasian man under treatment for hypothyroidism presented with acute-onset severe pain in his forearm for no obvious reason and was admitted to our emergency room. He eventually developed compartment syndrome which necessitated surgical decompression. Soon after surgery he complained of similar symptoms in his calves. By the time his hypothyroid status was confirmed, conservative treatment and orally administered levothyroxine gradually made the pain from his calves disappear, without further surgical treatment. Conclusion: Hoffmann's syndrome may precipitate a compartment syndrome in the absence of trauma.