Incompatibilty of parenteral drug admixtures is a subject with such wide ramifications that the problem of correlating all the factors will in future probably only be controlled by computer techniques. In the meantime, a knowledge of pH factors and a sound reference library, together with a pre-planned use of drug combinations wherever possible, will do much to alleviate the problem. Useful reference articles and facets of pH are discussed. Consideration should be given to avoiding admixtures of undocumented drugs in infusion fluids, and use should be made of a single drug injection at a separate locus.S. Afr. Med. J., 48, 1951 (1974).