Peroneal tendon tear is a relatively common cause of lateral ankle pain but often missed due to mixed presentation or low index of suspicion. Left untreated, peroneal injuries can lead to persistent ankle pain, instability and ultimately substantial functional disabilities. An isolated peroneus longus tear is rare with the lowest incidence rate compared to isolated peroneus brevis tear and mixed tear of both peroneal tendon. This is a case report of a 49-year-old lady with a chronic left ankle pain who ultimately underwent surgery for an isolated peroneus longus tear.