Background/Aims: The generic quality of life KINDL-R questionnaire is validated for use in children/adolescents ≤16 years. The aim of this cross-sectional investigation was to modify the KINDL-R questionnaire for use in adults and to validate its psychometric properties. Methods: Five items of the KINDL-R questionnaire were adapted and the newly developed KINDL-A(dult) questionnaire administered to 255 patients with hereditary and acquired bleeding disorders (mean age 53 years). Its internal consistency and convergent and divergent construct validity were investigated and confirmatory factor analysis was used to evaluate the latent factor structure. Results: The KINDL-A questionnaire showed satisfactory reliability, varying construct validity, but inconclusive factor structure. The KINDL-AB(rief) was developed by removing half of the items and combining 2 sub-axes. This led to factor loadings between 0.62 and 0.91 and increased overall fit (Goodness of fit > 0.8 and Root Mean Square Error of Approximation, RMSEA, < 0.08). Results were validated in 966 healthy blood donors (mean age 38 years). In this group, the KINDL-AB questionnaire showed factor loadings between 0.43 and 0.77, Goodness of fit > 0.95 and RMSEA < 0.05. Conclusions: The new KINDL-AB suggests sufficient to good psychometric properties in adult patients with hereditary and acquired bleeding disorders.