The ability of skin prick test (SPT) and histamine release from basophils (HR) to diagnose clinical type I allergy to egg and milk was investigated as compared with double-blind, placebo-controlled food challenge (DBPCFC) in 17 adults suspected of type I egg and/or milk allergy. In both SPT and HR, commercial allergen extracts commonly used for SPT were compared with fresh, standardized foods. With commercial extracts the overall sensitivities of SPT and HR were 0.75 and 0.56 respectively, and none of the tests showed concordance with DBPCFC. With fresh, standardized foods the overall sensitivities of SPT and HR were 1.00 and 0.89 respectively, and both tests now showed a significant concordance with DBPCFC (P<0.05). Specificity was only slightly improved in SPT, and unchanged in HR. Thus, the use of fresh, standardized foods significantly improved the outcome of both tests, as regards to sensitivity and concordance with DBPCFC. The diagnostic ability of SPT and HR appear to be strongly influenced by the allergen quality.