Psoriasis is basically a chronic skin disorder. It is diagnosed by the medical history that is the presenting history, the family history and the past history of the illness. The physical examination becomes a very important thing in diagnosing Psoriasis. That may need to examine his skin condition, the spread of the lesions, type of the lesions, type of the scaling, hairs, nails, scalp, joints etc. In some cases to identify the type of psoriasis, we may have to do the x-ray of the joints and we may have to do a biopsy to find out the exact type of Psoriasis. In some cases, we need to do blood tests to rule out other skin disorders.