Nail deformities may result from single episode of a trauma or chronic repetitive trauma. Onychophagia: Habit of nail biting is extremely common in children occurring in about 50% children. Nail biting is occasionally seen in adults and result from anxiety, tension, nervousness. In some adults it may be related to the periods of concentration and constructive activity. Nail changes include ragged distal edge of the nail plate, onychoschizia, transverse ridges and nail bed is exposed up to 50% or even more. Longitudinal melanonychia and periungual warts are also common. Paronychia and phalangeal osteomyelitis are other complications. Onychotillomania: It is an uncontrollable desire to pick or tear the nails and unlike nail biting it has association with psychological or psychiatric problems. Onychotillomania may take form of parasitophobia where small pieces of nail and surrounding fragments are picked off. Treatment includes psychotherapy, occlusive dressings and oral pimozide. Wash board nails: A nervous habit of repeatedly pushing back the cuticle on one or several finger nails can create washboard nails. Usually the proximal nail fold of the thumb is damaged by the index finger of the same hand and shows redness, swelling and scaling. This chronic mechanical injury results in series of transverse grooves with large central depression running down the nail termed as washboard nail. Dystrophia unguis mediana canaliformis: It is a rare nail dystrophy of unknown cause. It perhaps results from self inflicted trauma to the nail matrix. The deformity consists of central split in the nail plate, starting at the cuticle, which progress to the free edge. Extending from the centre are often a few cracks, projecting towards the lateral edges of the nail. This condition is symmetrical and most often affect thumb nails. Onychogryphosis and Onychauxis: Onychauxis is excessive thickening of the nail while onychogryphosis is excessive thickening with increased curvature of the nail plate. It is common in great toe nails. The nail is shaped like ‘Ram horn’ with brownish and irregular surface marked with transverse striations. The matrix produces nail plate at uneven rates which is not uniform. The fastest growing side of the nail determines the direction of the deformity. The most common cause for onychogryphosis is trauma from ill fitting shoes. It is also favored by secondary foot anomalies such as hallux valgus. It may cause discomfort and pain but usually asymptomatic, with only difficulty in clipping the nails. Fungal infections may also be associated with onychogryphosis. Ingrowing nails (onychocryptosis): Clinically ingrown nails start with pain and redness followed by swelling and pus formation. Lastly granulation tissue is formed which adds to the swelling and discharge. Spicule of the nail penetrates at the edge into epidermis of lateral nail fold, which gets separated from the main portion of the nail plate. The great toes are most often affected. It is mainly caused by ill fitting and high heeled footwear’s and secondly due to cutting nails in half circle instead of straight across. The condition may also be hereditary or constitutional. Ingrown nails have occurred in patients who had been treated with antifungal for fungal nail infection. After long term infection the nail is reduced in size and nail bed shrinks around it. When the infection is treated nail plate increases in size and nail bed is no longer large enough to accommodate the new nail and then penetrate onto lateral nail fold.