Psoriasis is a chronic skin disease that can occur in any part of the body. The only diagnostic tool available for psoriasis is skin tissue biopsy. Higher blood flow rate in the infected regions is a clinical symptom of this disease. When light is incident on the skin, the backscattered light carries information of the chromophore it interacts. Hence, the reflected light is processed to calculate the blood flow rate. This paper presents experimental results of blow flow rates measured on psoriatic patients at various stages of the disease. It is also found that skin blood flow can be used to distinguish psoriasis from a form of benign skin cancer.