The main purpose of this study is to investigate the correlation between socio-economic and demographic characteristics, health behavior, environmental factors and the severity of illness from infectious and non-infectious diseases among females of reproductive age (15-49 years old). Data used in this research were derived from The Health and Welfare Survey, conducted by the National Statistical Office in 1996. Samples consisted of 2,826 females who reported feeling ill or not well during the two weeks prior to the survey. Result indicated that there was a correlation between several socio-demographic factors and the severity of illness from both infectious and non-infectious diseases. The severity of illness was measured by length of time away from regular activities. For those who were ill with infectious diseases, they were absent from regular activities on average of 1.6 days. It was also found that education, number of members in the household, region and urban versus rural residence have an effect on severity of illness with infectious diseases, with regard to females who were ill with non-infectious diseases, they were absent from regular activities on average of 3.3 days. Factors that have an effect on the severity of illness included age, education and urban versus rural residence.