Since Hippocrates described ""Acute pain of the ear is to be dreaded"", the term ""Running ear and Hearing impairment"" is quite familiar in our life even in these days. During last two decades there has been a remarkable revival of interest in the middle ear. Advances in treatment of deafness, one of the chief complaints due to chronic suppurative otitis media, have been as spectacular as those in any branch of science of medicine. Originally a separate speciality, otology has so enlarged in scope that it may be said to occupy a wholly engrossing place within the general field of otorhinolaryngology. The paper presents clinical and statistical observations of 304 cases of chronic suppurative otitis media in Koreans, in whom the disease was confirmed by either way of clinical or radiological aspects, from January 1, 1966 to December 31, 1966, in the Dept. of Otolaryngology, Severance Hospital. Results may be summarized as follows. 1) Percentage ratio of chronic suppurative otitis media to the total number of ear diseases, middle ear diseases, and chronic middle ear diseases during aforementioned period was 24%, 63%, and 78%, respectively. 2) Male to female ratio was as 1.5 to 1, and peak incidence was in the age group of 20 to 29. 3) Perforations, according to Lillie's classification, in order of frequency were as follows : Type II, 230 cases (70.4%), Type III, 46 cases (14.4%), Type I, 43 cases (13.1%), and Type IV, 7 cases (2.1%). 4) Duration of disease since onset, the average was 9 years. 5) Subjective complaints in order of frequency were as follows : otorrhea 215 cases (43.2%), hearing impairment 154 cases (30.9%), otalgia 60 cases (12.2%), tinnitus 30 cases (6.1%), headache 30 cases (6.1%) and intracranial complication signs 8 cases (1.5%). 6) Character of otorrhea may be decribed as ""intermittent, mucopurulent, or purulent discharge"" (93.2%). 7) Classification of hearing loss was Conductive 61.1%, Sensorineural 22.2% and Mixed 16.7%. 8) Maximum hearing loss of speech range, in the cases of central perforation was as follows : round shape 45.9±6.78, oval shape 40.6±5.89, kidney shape 57.5±7.03, heart shape 53.0±5.61, and in the cases of total perforation 75.0±6.81, and in the cases of Shrapnell's membrane perforation 56.0±14.08. Percentage ratio of hearing loss in speech range was as follows : Round 36% oval 34%, kidney 54%, heart 45%, total 85 and Shrapnell's membrane perforation 56%. 9) Pneumatic type in healthy ears was nearly 5 times as frequent as in cases of infected ears. The sclerotic type in infected. Ears was nearly 5 times as frequent as in cases of healthy ears. The percentage of cholesteatoma in infected ears was 24.2%. 10) Diseases complicated with Nose and Throat infection was 38 cases (12.5%), including chronic maxillary sinusitis 27 cases (71%), chronic follicular tonsillitis with adenoid vegetations 7 cases (18.4%), and allergic rhinitis 4 cases (10.6%). 11) Procedures performed for mastoid operations were radical 24 cases (61.5%), simple 10 cases (25.6%), modified 5 cases (12.9%) and for the tympanoplasty, 50% simple, 100% modified were performed.