We report a case of anterior thigh compartment syndrome, which occurred after man's thigh was bruised after flipping repeatedly over his bike and being hit by the frame of the bike nearly at around 6 pm. The next day at 1:30 am, he was admitted to the hospital. The initial presentation was a hematoma, and the patient was kept in bed with local cooling. The compartment syndrome of the thigh (CST) diagnosis was made around 6:00 pm when the level of pain was interpreted as disproportionate to the treated lesion; anterior compartment pressure measure was 84 mmHg. A compartment fasciotomy was performed. It is difficult to diagnose a CST in case of muscular contusion as the latter causes symptoms that are similar to CST. A conservative treatment without fasciotomy was carried out by several authors, especially in sportsmen showing a CST following contusion. This conservative treatment implies close monitoring of intramuscular pressures and adjuvant measures (bed rest, holding the thigh at the heart level and oxygenotherapy).