Ankylosis is defined as a fusion of alveolar bone with dentin and/or cementum and may occur at any time during or following active eruption. Ankylosed teeth maintain existing occlusal levels while adjacent teeth continue to erupt via deposition of alveolar bone. This may result in the clinical appearance of depression or submergence of ankylosed teeth below the occlusal plane. It is found more frequently in children of late mixed dentition and in mandibular primary molars. The problems arising from ankylosed teeth, due to their submerged positions, are elongation of the antagonist, tipping of the adjacent teeth, loss of arch length, food impaction and subsequent destruction of periodontal tissue, disturbance of succedaneous tooth eruption. The author observed several cases of ankylosed primary molars and properly managed. Following results were obtained. 1. Severe infraoccluded ankylosis results in loss of arch length and undesirable effect on eruption path of succedaneous tooth, therefore early diagnosis and management are important. 2. The teeth without problems may be examined periodically and restored in order to maintain the normal occlusal function.