1. The personal background and army experience of a group of soldiers overseas has been studied and compared. These included hospitalized psychiatric casualties of which about a third were psychotic and the rest were psychoneurotic. Members of the hospital medical detachment on active duty were also interviewed and the data concerning them tabulated.2. Of the psychotics, the smaller number were acute psychotic episodes with recovery within a few weeks of the onset; the larger were apparently more chronic psychotic developments.3. The presenting complaints of the entire group of psychoneurotic patients were listed and tabulated. Only a few patients had only a single complaint. The rest complained on the average of at least 3 or 4 different issues.4. Of the psychotic patients, most were considered to be in line of duty. A comparatively few were not in line of duty. Less than half of the total psychotic group had been overseas for more than a year and about two-thirds of them had served in the tropics.5. Of the psychoneurotic patients, the greater number were considered to be not in line of duty.6. Certain leading contrasts between these two groups were evident.7. Members of the hospital detachment were interviewed and the tabulated results showed them to be closely comparable as to background factors with the group of psychoneurotic patients considered "line of duty Yes." A group of new recruits to the detachment were similarly examined and the results as to background and personality were almost exactly the same as in the original group, although the smaller group had undergone no combat experience, none of them had been in the tropics for more than a month and none of them had contracted tropical disease.Abstract Teaser