Pyomyositis is a bacterial infection of skeletal muscle common in the tropics. Pyomyositis has historically been rare in temperate regions. However, the epidemiology is changing, and over the past decade, the number of cases in the United States and Europe has increased significantly. One major factor appears to be the increase in community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. This pathogen now accounts for most of the skin and soft tissue infections throughout much of the United States. Most community-associated MRSA infections carry specific virulence factors, most notably the Panton-Valentine leukocidin gene, known to increase invasive capability and predispose to abscess and deep tissue infections. We report a case of a young healthy woman who was initially treated as an outpatient for tendonitis. She presented 3 days later to the emergency department where she was diagnosed with upper extremity pyomyositis complicated by compartment syndrome. A fasciotomy was performed in the operating room, and intraoperative cultures grew MRSA. She did not have any traditional risk factors for the acquisition of health care-associated MRSA. Her subsequent course was complicated by osteomyelitis of the proximal radius. This is the first report of pyomyositis complicated by compartment syndrome in the emergency medicine literature. This case emphasizes the need to remain vigilant for deep muscle infections given the evolving epidemiology. It also highlights possible complications of pyomyositis including the rare but serious complication of compartment syndrome.