Objective: Removal of third molars (3Ms) is one of the most common surgical procedures performed by dental surgeons. 3Ms that are associated with pathologic changes such as infection, nonrestorable caries lesions, cysts, tumors, and destruction of adjacent teeth and bone are under consensus for their removal. However, debate exists regarding the prophylactic removal of asymptomatic impacted 3Ms. This review attempts to establish indications for prophylactic extraction of 3Ms. Method and Materials: Clinical experience and a summary of the literature are presented concerning the effects of retained 3Ms in relation to caries and periodontal disease, dental arch changes and anterior crowding, cysts and other etiologies, mandibular fractures, temporomandibular pain, and aging of bone. Results: Nearly half of impacted 3Ms are associated with some form of pathology, most frequently caries (20%) and periodontal disease (17%). They increase the probability of fractures and their presence results in difficult fracture reduction and a higher rate of complication. The number of 3Ms decreases rapidly with age, with only 31% remaining at 38 years of age. Conclusion: Preventive removal of 3Ms at a young age is justified because retained 3Ms are at high risk of developing various pathologies. In addition, at older ages extraction of 3Ms becomes more complex, with an increased rate of complication due to deteriorated systemic physiologic conditions and changes in bone physiology. Keywords: asymptomatic, extraction, impacted, preventive, third molars