279 cases of epistaxis were observed during 2 years from January, 1969 to December, 1970. The observation undertaken by the author was the influences of the temperature, barometric pressure and relative humidity, pertaining to general considerations. The results were as follows ; 1. In etiological differentiation among the 279 cases of epistaxis, 78 cases were caused by local factors, 29 cases by general factors and 172 cases by unknown factors. 2. In differentiation by the induced diseases, anomaly of nasal septum was the most common one among the local factors and hypertension among the general factors. 3. Epistaxis was most frequently observed between 10 to 20 years of age and more frequent in male than female with the ratio of 3 : 2. 4. Existaxis was more frequent in the left nasal cavity than the right. 5. Most of epistaxis were from the anterior nasal cavity (96.6%) and few cases were from the posterior nasal cavity : The most frequent site of epistaxis was Kiesselbach's plexus (84.84%). 6. In seasonal frequency, epistaxis was most frequently observed in April, May and June. 7. In influences of the temperature, barometric pressure and relative humidity on the frequency of epistaxis, the increase of epistaxis was found on day with the severe fluctuation of temperature in which the thermometer, after having reached a minimum, turned upward, or the reverse ; especially on day with sudden fall of temperature and decreased humidity. The increase of epistaxis was also found on days with the rapid fall of barometric pressure, or with the well-marked gap between maximum and minimum barometric pressure.