A field test using Nophazin (drying off period therapeutics) was done from May, 1989 to October, 1989. 299 quarters of 75 cows from 28 herds were tested. The results were summarized as follows. 1. At the day 7 after parturition, CMT-was 81.60%, clots were removed perfectly, removal rate of hard, hot, pain was 99.6%, only one hard 0.35% was maintained. Recovery rate of general symptoms was 100%. 2. Recovery rate in Nophazin treatment was 100% in Micro-coccus SPP, Corynebacterium SPP, and unisolated, 97.06% in Enterobacterid SPP, 95.58% in Staphylococcus SPP, 91.67% in other Bacilli, 89.19% in Streptococcus SPP, Overall recovery rate was 95.32%, And fungi did not react. 3. The ratio of isolated microorganisms was Staphylococcus SPP 49.8%, Streptococcus SPP 16.3%, Enterobacteria SPP 15.0%, Micrococcus SPP 7.9% Corynebacterium SPP 4.4%, Pseudomonas SPP 2.6%, Bacilli 2.6% and Fungi 1.3%. 4. The range of sensitivity of each microorganism to therapeutics is as follow : Staphylococcus SPP 61.1∼94.7%, Streptococcus SPP 51.4∼91.9%, Micrococcus SPP 44.4∼94.4%, Corynebacterium SPP 70∼80%, Enterobacteria SPP 11.8∼88.2%, and other Gram negative bacilli 8.3∼83.3%. Overall sensitivity was in the range of 50.4∼92.0%, Microorganisms showed the highest sensitivity (80∼94.7%) to Nophazin. 5. New intramammary infection rate was 3.96% (9 strains) at paturition, 8.37% (19 strains) at the day 7 after paturition. Persistent organism wits 6.17% .(14 strains). 6. There was no side effect of Nophazin treatment.