Two male sarcoma patients developed a compartment syndrome in the thigh after the harvest and direct closure of the anterolateral thigh flap donor site. In each case, the absence of signs or symptoms led to a delay in diagnosis and treatment. Although use of the anterolateral thigh flap is increasingly popular for soft tissue reconstruction, this complication has not yet been reported. The cases and likely etiological factors are discussed as are recommendations for avoiding this devastating complication.