0.3 ml. concentrated HC1 + 2 ml. urine are heated for 17 minutes on a boiling HOH bath in special glass-stoppered 12 ml. centrifuge tubes. After cooling, 4 ml. ethyl ether are added, and the mixture shaken mechanically for 1 minute. After sucking off the urine, the ether is washed with 2 ml. 2N NaOH, followed by 2 4 ml. HOH washes. Each wash is shaken 100 strokes. The ether is dried with Na2SO4, then filtered through a sintered glass filter which is washed twice with ether. The pooled ether washes and filtrate are evaporated to dryness (50[degree]C); then 0.24 ml. fresh mixture of 1 part 2% m-dinitrobenzene and 2 parts 1.25 N alc. KOH is added, shaken to dissolve residue, incubated 60 min. in dark at 25[degree]C. Add 3.76 ml. absolute C2H5OH, and read in spectrophotometer. For the NaOH wash, a single wash of 4 ml. HOH, without shaking, followed by 15-20 NaOH pellets, and shaking for 100 times before filtering may be substituted. Technique permits 60-70 analyses per day per technician with accuracy comparable to that obtained by the Hamburger procedure.