Research has shown a generally positive correlation between a person's propensity for illness and certain psychological variables. To investigate the relationship between an individual's age, sex, and degree of subscription to each of Albert Ellis' 10 irrational beliefs and their frequency and type of illness, 122 adults completed the Irrational Beliefs Test and an illness questionnaire. In general, the older subject with a high need for approval, competency, and achievement, a low need to find the perfect solution to every problem, and, to a lesser extent, a high dependency on other stronger persons correlated with more organ systems being affected by illness, more chronic illnesses, and, to some extent, a greater total frequency of illness. This was true more often in females than in males. The findings suggest that subscription to irrational beliefs in combination with age and sex tends to account for some of the variance in the selective process of illness not accounted for by natural environmental factors. (Author/JAC)