In order to understand the quality of Oxytetracycline products, 110 samples were purchased in Taiwan area during the peried between September 1985 and June 1986. The potency of samples was determined by the Ferric chloride colorimetric method. Results showed that 80 of 90 domestic sample (88.9%) and all 20 imported samples meet the requirement of CFR 1980 and MRAP 1982, 90~120% Potency.