Psoriasis vulgaris is an inflammatory disorder charachterized by red scaling plaques on the skin surface. The musculoskeletal system may also be affected with an inflammatory arthritis, which at times may be debilitating. In plaque-type psoriasis, the most frequently encountered form of psoriasis vulgaris, well demarcated pink to red erythematous plaques with adherent white to silver scale are present on the skin surface. The nail changes of psoriasis occur in many morphologic forms. The typical nail plate pitting is due to parakeratosis in the nail plate formed in the proximal nail matrix. Leukonychia has been attributed to involvement of the midportion of the nail matrix by psoriasis. Onycholysis occurs because of hyperproliferative epithelium in the nail bed. The degree of subungual hyperkeratosis may be dramatic and may result in lifting and crumbling of the nail plate. The splinter hemorrhages seen through the nail plate originate from capillary proliferation in the papillary dermis of the nail bed. Oil drop lesions develop from the nail bed and have a characteristic yellow appearance as seen through the nail plate.