Previous authors have reported ranges of normal coproporphyrin excretion values which differ by several hundred per cent. The present study was undertaken to determine whether the scatter of normal values is a result of differences in analytical methodology. It is shown that the values obtained for copro-and uroporphyrin are the same whether urine extracts are assayed by spectrophotometry or fluorometry. Equivalent results are also obtained with solvent extraction and alumina adsorption technics. The coproporphyrin range for our normal adult population (0-161 µg./day) is intermediate between the literature values, while the uroporphyrin range (0-26 µg./day) is compatible with the reports of most workers. An improved solvent extraction method for urinary porphyrins is presented in which n-butanol is used to isolate uroporphyrin after removal of the coproporphyrin fraction.