Opportunity was taken to study the morbidity of the more important groups of diseases affecting R.A.F. personnel with reference to the climatic conditions at Mingaladon, nr Rangoon, from February to July 1946. Temperature recordings (both wet and dry bulb), together with figures for humidity, were kindly provided by the Meteorological Forecast Centre at the station. The climatic conditions may be divided into two distinct periods: the pre-monsoon from mid-February to mid-May, and the monsoon itself which followed and continued throughout June and July.