The subject field of clinical allergology deals with many hundreds of different allergens from all parts of the human environment, and the number steadily increases. Not all of the allergens are strictly defined in chemical terms, and procedures for detection of antibodies against allergens in humans vary. This document deals with the presentation of request and report on such properties according to some international rules and the allocation of code values representing the concept delineated. The coding scheme thus prepared is imperfect and needs further elaboration as allergens become more well defined. It is a step toward harmonization, in particular as concerns the coding system applied. The net outcome is a coding scheme for use in electronic transmission.