made to be reasonably comprehensive in the range of tests described; hence, not only have some rather older ones been re­ tained, but also some very recently introduced ones included. It is appreciated that practice varies widely from laboratory to labora­ tory with respect to protocol, sample collection, methodology and quotation of reference ranges, and no doubt also from clinician to clinician, particularly regarding interpretation of results. In paedi­ atric work, micromethods will demand much smaller volumes of blood than those stated here, which relate generally to adult medi­ cine. The account, therefore, must be seen as a guide to practice rather than as a recipe; it is in no wayan attempt to standardise procedures, which depend on the local requirements.