Objective: This study aimed at identifying the minimal incidence and prevalence rates of psoriasis and determining factors affecting occurrence and severity of the disease. Methods: The study design can be differentiated into two components. The first one was a descriptive study to determine incidence and prevalence through record study of all psoriasis patients attended the selected outpatient clinic under study during the year 2000. The second one was a case-control study to define factors affecting occurrence of psoriasis and was conducted among 200 psoriasis cases and 200 control subjects. Psoriasis cases were used to identify factors that might affect the severity of the disease through a nested case-control study. Results: The overall psoriasis incidence and prevalence in Kuwait were 0.11% and 0.45% respectively. Male gender, smoking, sunbathing, having arthritis or pharyngitis, liver impairment and positive family history of psoriasis were significant risk factors for developing psoriasis. Alcohol consumption and numbers of patches ≥5 at initial presentation were risk factors for progression of psoriasis. Meanwhile, family history of psoriasis and treatment with Psoralen Ultra Violet A [PUVA] were protective variables against progression of the disease. Conclusion: The prevalence of psoriasis is low as compared to other countries in the area. Psoriasis is more liable to occur in smoker male with family history of psoriasis. Treatment with PUVA may help against exacerbation of psoriasis.