Introduction: A stooped posture is a main clinical feature of Parkinson's disease (PD). The assessment of posture is important to measure treatment effects. The aim of this study was to investigate the reliability of a standardized postural rating tool, to calculate minimal detectable change scores and to assess the role of gender and age. Methods: Two independent raters assessed total camptocormia (TCC), upper camptocormia (UCC) and Pisa angles of 192 PD patients and 78 healthy controls (HC) with the free NeuroPostureApp©(http://www.neuroimaging.uni-kiel.de/NeuroPostureApp). Reliabilities and linear models were calculated for different effects. Three subgroups were defined based on two thresholds (mean+2SD of HC and PD): A) normal, B) presumed stooped/lateral bended posture and C) postural disorder. Results: Intraclass correlation coefficients ranged between 0.71 and 0.95 for the interrater and test-retest reliability of the three angles. The minimal detectable change values in the PD patients were 3.7°, 6.7° and 2.1° for the TCC, UCC and Pisa angles, respectively. Men had a more stooped posture than women (p < 0.05). Patients with PD had a worse posture than HC (p < 0.001) in all three angles. For the TCC angle, 39.1% of the patients had a normal posture (<17.4°), 47.9% a presumed stooped posture (>17.4°, <30.2°) and 6.3° had camptocormia (>30.2°). Conclusions: The NeuroPostureApp© is reliable. Our results confirmed gender differences and the progression of postural deviation in PD patients with age and empirically support the ≥30° TCC angle as a defining criterium for camptocormia. Diagnostic criteria for UCC and Pisa syndrome should be further explored in future studies.