Skin prick testing remains the most popular way to confirm an IgE-mediated allergic response. This study was performed to compare the accuracy and sensitivity of two skin testing modalities (serial endpoint titration and skin prick testing with 2 different in vitro assays.) In 52 atopic patients serial endpoint titration showed a higher degree of sensitivity in evaluating skin response in less sensitive reactors. At higher degrees of reactivity in individual patients there was good correlation between the 3 modalities. Identifying patients who are less sensitive reactors is important, so that they can be started on immunotherapy. In fact, an informal survey of low-reacting patients treated with immunotherapy showed a high degree of success.