An allergic response is the hypersensitive immune response to a substance which is normally harmless or would not cause an immune response in everyone. An allergic response can cause several symptoms such as itching, inflammation and tissue injury. The manifestation of allergies is recognized in the form of urticaria, swelling, burning, pain, and dryness of the mucosa, stomatitis. radioallergosorbent test (RAST) which is the radioallergosorbent test used for the confirmation of allergic reaction in the body. This test specifically deals with the IgE antibodies which are responsible for the allergic reactions on the body. It is very essential to crosscheck the exact history related to allergy. Individual sensitivity and population sensitivity, both are equally responsible for skin allergy are the factors which are to be considered. Skin tests become negative under conditions of severe allergic reactions which is determined by graded therapy by freedom from contact and using epinephrine administration. RAST test is a two-stage procedure. RAST-test is performed according to the guidelines of European Committee on Antimicrobial Susceptibility (EUCAST). The reliability of the test is high compared to other skin tests. Specificity based on two radioallergosorbent tests is high as 90% for inhaled allergens. It shows excellent reproducibility across a full measuring range with the help of the calibration curve. The RAST test is considered to be extremely sensitive. It shows high specificity which binds to allergen-specific IgE. This article mainly deals with the RAST procedure, advantages and disadvantages of the test.