Onychocryptosis is a pathologic condition of the nail apparatus in which the toenail damages the nail fold. It is a common condition provoking pain, inflammation, and functional limitation. It principally occurs in the hallux. Onychocryptosis is one of the most frequent complaints regarding the foot and accounts for many clinical consultations. The disorder has been classified in terms of the stages of the pathologic condition. In our practice, we discovered a clinical entity that was not previously classified in the literature. We classify onychocryptosis into stages I, IIa, IIb, III, and the new stage IV. A treatment plan is offered for each stage of this classification, with both general and specific indications given. In onychocryptosis treatment, it is important to select the surgical technique best suited to the patient’s particular clinical situation. (J Am Podiatr Med Assoc 97(5): 389–393, 2007)