This case report details a rare occurrence of iliacus muscle hematoma in a 17-year-old female during physical therapy, particularly after an extensive hip extension exercise. The case outlines the patient's experience of intense pain and subsequent development of motor weakness and hypoesthesia, revealing diagnostic findings from electromyography (EMG) and nerve conduction studies. Treatment included a combination of modalities like TENS, infrared, microwave therapy, and manual therapy, which successfully improved the patient's condition as evidenced by follow-up MRI and clinical assessments. This report emphasizes the importance of physical therapists’ awareness of such rare complications and the need for individualized treatment plans, cautious biomechanical assessment, and continuous education in physical therapy practice. It highlights the necessity of a comprehensive approach in managing unusual and complex cases, showcasing the adaptability required in physical therapy.