We studied 45 children who presented with an inversion injury of the ankle. The clinical signs suggested injury to the distal growth plate of the fibula, but the plain radiographs appeared normal. Ultrasound examination of the joint in 40 patients showed a subperiosteal haematoma consistent with a growth-plate injury in 23 (57.5%). Children who had been treated with a tubular bandage and crutches by random selection had a mean time to return of normal activity of 14.22 days compared with 21.60 days for those treated with a plaster-of-Paris cast (t = 3.60, p = 0.0032; d = 7.38, 95% CI 3.0 to 11.8). We conclude that children with inversion