In Korea, owing to effective vaccination, occurences of poliomyelitis begen to decrease rapidly from 1964 and in recent years less than 10 cases of acute infection are being reported annually. However, patients crippled with poliomyeltis residua, mainly the legacy of the many epidemics of 1950s, and early 1960s, are many and pose a social and national problem as well as a personal and family ordeal. We reviewed 536 patients with residual poliomyelitis admitted and treated at Seoul National University Hospital during the past 18 years, from 1963 to 1980 They were divided into four chronological groups; the first, 1993 to 1968, the second 1968 to 1973, the third, 1974 to 1977, and the fourth, 1978 to 1980, In each group, based on in-patient records, and out-patient records, epidemology, deformities, and treatment were extensively reviewed. The followings are the outcome of this investigation 1. The male-to-female ratio was 53.7%: 46.3%, The male majority, distinct in the first group with 63. 7%, became less conspicuos in the fouth group with 50. 3%. 2. Average age oe admission, which was 10. 7 years in the first group, had increased decidedly to 17. 8 years in the fourth group. 3. The age of onset was most frequent between 1 to 2 years with 45.8% and next frequent between 7 to 12 months with 23. 5%. The ages below 5 years occupied 97. 6% of the cases. 4. The year of onset was most frequent from 1961 to 1963 with 28.7%. The incidence markedly and steadily decreased thereafter. 5. 94. 5% of the cases were unvaccinated. The remaining cases, except one, had had incomplete vaccination. 6. Fever, with 74. 0% was by far the most frequent initial symptom. Vomiting and diarrhea were the next frequent symptoms. 7. Of the 60% of the patients who had had any previous treatment, 25. 9% had operations and 20. 4% had braces and crutches. 8. Average number of admissions per patient were 1. 7 and average number of operations were l. 9. Average length of hospitalization was 39. 2 days. 9. 23. 6% of the patents had hip deformities, of which flexion defermity was most frequent with 4. 7%. Soutter fasciotomy or Campbell operation was employed in order to correct flexion deformity. In the earlier groups, Mustard operation, Sharrard operation, Ober-Barr operation, and pem-berton osteotmy were commonly practiced, whereas in the later groups, Thomas-Thompson-Straub operation, combined Thomas-Thompson-Straub and Ober-Barr operation, Salter osteotomy, Chiari osteotomy, Steel osteotomy were favored. 10. 45.2% of the patients had knee and leg deformities, of which flexion deformit; was most frequent with 14.5%. Flexion-valgus-external rotation deformity and flexion-valgus deformity with 4.6% and 4.5%, respectively, followed next. 11. 83. 9% of the patients had foot and toe deformities, of which equinovarus deformity occupied 6. 5% equinovalgus deformity 6.8%, and clawing of great toe 25. 2%. Triple arthodesis was done most frequently with 45. 9% of the cases, or 282 feet. Jone's operation or its modification, Tendo Achilles lengthening, plantar fasciotomy, and Peroneal tendon transfer were also frequntly performed. 12. There was leg length inequality in 90%. of the cases, Epiphysiodesis and femoral shortening were carried out, except for 4 cases of stapling in the earliest group, and femoral lengthening was done in 3 cases. 13. Spineal deformity was found in 19.7 % Of the cases, of which scoliosis was most freqent with 11. 5%. 7% of the cases had pelevic obliquity. Lumbodorsal fasciotomy, and postrior spinal fusion with Harrington instrument were carried out in order to ameliorate these deformities. 14. Deformities in the upper extremity were found in 3.6% of the patients. Procedures carried out inclulded shoulder fusion, Saha's operation, Steindler's flexorplasty, sternocleidomastold transfer, wrist fusion and opponensplasty, etc. 15. Generally, there was marked improvement of disability after treatment. The patients having moder.ate to severe limping decreased from 41.3%, preoperatively, to 25% after operation.