This is the result of the annual statistic analysis of thoracic and cardiovascular surgical cases in 1991, Korea. 14,715 cases of surgery[thoracic 8,995/cardiovascular 5,720] were done by 53 institutes replied. The order of frequency of cell type in primary lung cancer was squamous [62.3%] / adeno [23.9%] / small [6.4%] / adenosquamous [3.0%], and in mediastinal tumor, neurogenic[27.l%] / thymoma [27.1%] / teratoma[26.4%] / congenital cystic[12.0%]. Surgery for tuberculosis was decreased to 15.8% of overall infectious disease from the recent 6 year`s average 35.7%. In general thoracic surgery, the single most frequent operation was closed thoracostomy[4,047 cases] for pleural pathology. The ratio of congenital to acquired heart disease was 2:1, and acyanotic to cyanotic was 3:1. The order of frequency of congenital acyanotic heart disease was VSD [45.6%] / ASD [25.6%] / PDA [20.4%] / PS [2.9%], and that of cyanotic heart disease was TOF [42.6%] / PA [12.9%] / TGA [9.9%] / DORV [8.8%]. In 1,364 cases of valvular surgery, single mitral pathology was the most frequent candidate[729 cases, 53.4%]. In 243 cases of coronary surgery, bypassing graft materials were great saphenous vein[41.6%], internal mammary [39.5%], and artificial vessel[18.9%]. There were no specific differences in aortic surgery, assisted device implantation, and antiarrhythmic surgery as compared to previous study. This nation-wide inquiry will be continued and reported annually by KTCS Society.