(1) A Study has been made of the disease incidence in a variety of groups admitted to a Base Psychiatric Hospital. (2) The relationships between the group incidence of anxiety state and manic - depressive psychosis and between hysteria and schizophrenia have been indicated. (3) The influence of the standard of personnel selection and morale on the disease incidence has been discussed. (4) The importance of the quantitative factor in diagnosis in military psychiatry has been stressed and a method of assessing it has been described. (5) An argument has been put forward for the use of the psychiatrist in the positive aspect of personnel selection in addition to his usual role of weeding out the unfit.