Various methods of adjusting urinary concentrations of heavy metals and various organic metabolites are discussed. Those involving specific gravity, osmolality, and creatinine have been studied in detail. Data indicate adjusted values are better than unadjusted ones. No general superiority is shown, however, of creatinine over specific gravity or osmolality. But in cases where urine samples contain sugar or protein the specific gravity adjustment may be seriously in error. It is, nevertheless, recommended that the specific gravity adjustment to 1.024 be used since data in the literature are most frequently reported in this way. The creatinine adjustment to be comparable should be to 1.8 grams cireatinine.