Pain, R. W., and Oldfield, R. K.: Survey of T3 methods of thyroid function. Techn. Bull. Regist. Med. Techn., 39: 139–141, 1969. A comparison of results from six T3 methods recorded in the literature was difficult because of wide variation in the type and number of subjects and in percentage limits used for reference ranges, as well as in the degree of selection and number of abnormal cases tested, and because of the general paucity of useful information concerning the reproducibility of the tests. Consequently, only general conclusions are possible. Impressive results are obtained for hyperthyroidism with five technics and for hypothyroidism with four technics. For reasons of ease of performance, the T3-charcoal-hemoglobin assay would appear to be the method of choice for routine T3-testing.