The method described is well suited to routine analysis. After digestion with a sulphuric-nitric acid mixture the iron in the blood is detd. by a modification of Hill''s a,a''-dipyridyl procedure. The intensity of the red color developed was found to be almost directly proportional to the Fe content. The Fe content was evaluated from a graph constructed by means of measurements of a series of standard solutions in a Lovibond tintometer. Comparison of the present method with the usual thiocyanate procedure gave results which agreed to within 5%.