Fly-bombing is not always concentrated, for isolated explosions may occur at any time. There are also numerous if uneventful alerts. Thus there is a state of continuous uncertainty which might be expected to affect psychoneurotics considerably. I therefore set out to investigate the reactions of my patients during approximately ten weeks' concentrated fly-bombing. There were 620 soldiers—9 male officers and 121 auxiliaries—a total of 750 cases, all stationed in the London district. They were referred to me for various psychiatric reasons, by no means on account of anxiety due to bombing; nor was referral on account of fear of bombs necessarily indicative of special apprehension on the part of the patient—in some cases indeed it obviously only indicated anxiety on the part of those making the referral!