Na monofluoroacetate was admd. to Holtzman white rats in doses of 0.3-50 mg./kg. and the citrate content of kidney, thymus, brain, spleen, heart, liver and tumors determined after 20 min. to 48 hrs. As in previous studies liver and tumors did not accumulate citrate, but the remaining tissues did, with the max. occurring in all cases with a dose of 3.5 mg./kg. at 3-6 hrs. after the injn. As a standard procedure this dose was recommended for the study of certain phases of the metabolism of individual tissues in vivo.