Following an acute ankle inversion trauma, the aim of the diagnostic strategy is to rule out a fracture and/or lateral ankle ligament rupture. Plain X-rays are indicated when weightbearing is impossible (the patient cannot take at least four steps) and/or if there is pain on palpation on the posterior aspect of the lateral or medial malleolus. This applies to the period directly following the trauma as well as 4-5 days later. In the first forty-eight hours after trauma, physical examination cannot distinguish between a distortion and a lateral ligament rupture. In a patient with a painful swollen ankle after an acute inversion trauma, a compression bandage is applied and the patient is advised to elevate the leg and to perform ankle movements, notably dorsal extension. Weightbearing on the extremity may be allowed as soon as the pain allows. A few days later, when pain and swelling have subsided, delayed physical examination for detection of a lateral ligament rupture is performed. Delayed physical examination four to five days after inversion trauma has good interobserver agreement. Additional diagnostics such as radiography, arthrography, ultrasound investigation and MRI are expensive and give no further information. In a patient with a simple distortion an elastic bandage for a few days can be applied. The patient is instructed to resume normal walking as soon as possible. Functional treatment with inelastic tape bandage or a brace application for five to six weeks is the treatment of choice for an acute lateral ankle ligament rupture. The aim of treatment is restoration of a normal range of motion within two weeks and a stable ankle at long term follow-up.