It has been suggested by Dr. Halstead that magnesium di-potassium EDTA could cause the blood of the recipient to become more acidic, therefore making the chelating effect of the EDTA less effective. To test this hypotheses, we measured the ph of venous blood both before, and 40 minutes after a 365 mg magnesium di-potassium EDTA suppository. The results were that the ph of the blood rose from 7.37 to 7.66. Thus, contrary to Dr. Halstead's supposition, magnesium di-potassium EDTA has an alkalizing, not an acidifying effect on blood ph values. Since magnesium and potassium are both alkaline elements, the alkaline result was to be expected.