The histories of 17 years old clinically normal subjects show that 10% of them had functional disturbances or abnormalities in behaviour which are not to be considered as indications of latent neurotic development. Significant differences in EEG, size distribution, and reaction of the circulatory system during psycho-emotional stress (low-pressure chamber testing) may indicate a disharmonious physical maturation with increased disposition to circulatory lability and psychological abnormalities. The good intellectual performances and the favourable prognosis with regard to flight training are reasons for not disqualifying this group of applicants.