Objective: The objective of the present study was to calculate sex- and age-specific normative values for health-related quality of life (HRQoL) in Germany using quantile regression. Furthermore, we investigate the estimates of these normative data to and to predict the improvement of QoL-AGHDA scores in the German KIMS cohort during growth hormone treatment. Design: Normative data of HRQoL was assessed by quality of life assessment of growth hormone deficiency (GHD) in adults (QoL-AGHDA) in a representative sample of the German population (n = 4172). Corresponding data for 888 patients with GHD were retrieved from the German KIMS cohort (Pfizer International Metabolic Database). Results: The overall mean QoL-AGHDA score of the general population was 4.8 ± 5.2. ANOVA indicated that variability in QoL-AGHDA scores did not differ significantly across gender (p = 0.20), whereas age was a significant predictor (p < 0.001). Given the QoL-AGHDA score distribution of the general population, we calculated reference values based on quantile regression. In KIMS patients we observed significantly higher QoL-AGHDA scores, 7.9 ± 6.5 (p < 0.001), before GH treatment. The optimal predictive QoL-AGHDA score was 6 (70th percentile) with a sensitivity of 0.57 and a specificity of 0.70 in ROC analysis. Furthermore, a baseline QoL-AGHDA score above the 70th percentile allowed predicting an improvement of QoL by GH treatment. Conclusions: This study established normative reference values for the QoL-AGHDA in a representative sample of the German population. Based on these normative data a QoL-AGHDA cut-off value for prediction of improvement was investigated for the German population, which may facilitate clinical assessment of HRQoL response to GH replacement for patients with GHD.