So far any success has not been made in finding any harmless and cheap preservative which is effective in keeping quality of " Kamaboko ". Some preservatives which have been permitted to use for our purpose by the Ministry of Public Health and Welfare of the Japanese Government were found to show but little effectiveness at permitted level. On the other hand, Tomiyama et al have previously reported that the spoilage of round fish was markedly retarded by chlortetracycline (CTC). The present paper deals with prolongation of storage life of "Kamaboko" by treating with CTC and/or DHA. 1. Without casing, CTC was found ineffective when it was either smeared on the surface or mixed into the paste. The combination of CTC and DHA which were mixed into the paste at levels of 40 ppm and 0.2 %, respectively, showed prolongation of shelf life as long as five days in contrast to three days in the control group. However, when both preservatives were smeared on the surface, the combination was remained ineffective (Tables 1 and 2). 2. When the paste containing CTC and DHA was covered with cellophane casing smeared with CTC and DHA, the storage life was four days in contrast to three days in control group (Table 1). 3. When the cellophane casing was applied on the paste containing 10 ppm CTC prior to steaming was effective in extending the storage life as long as four days in contrast to two days in control group with casing. When "Kamaboko" was prepared with ground fish flesh which was washed with 10 ppm CTC solution and further added with 10 ppm CTC, the storage life was appreciably extended (Table 3).