In this case, a clear pathway for eruption was provided for the mandibular left first permanent molar by reducing the distal surface of the primary molar. The occlusal surface was also surgically uncovered to remove any possibility of a mucosal barrier. It was thought that the loss of arch length was not too great a sacrifice if the tooth could be brought into occlusion. The tooth proved not to be ankylosed and was, therefore, able to erupt into occlusion. The patient may have some crowding in the mandible; however, it appears to be within normal limits and no further orthodontic treatment is anticipated. When the relative simplicity of treatment is weighed against the severity of the consequences of untreated cases of ectopic eruption, it is suggested that treatment should be started as soon as the condition is diagnosed, to establish a normal eruption pathway and avoid any detrimental effects on a developing occlusion.