This study aimed to identify and compare age stereotypes of registered nurses and supervisors in clinical inpatient settings. Generic qualitative study using half-standardized interviews. Nineteen face-to-face interviews and five focus groups (N = 50) were conducted with nurses of varying levels at a hospital of maximum medical care in Germany between August and November 2018 and were subjected to structured qualitative content analysis. Reflecting the ageing process and cooperation in mixed-age teams, nursing staff and supervisors defined similar age stereotypes towards older and younger nurses reminiscent of common generational labels 'Baby Boomers' and Generations X. Their evaluation created an inconsistent and contradictory pattern differing to the respective work context and goals. Age stereotypes were described as both potentially beneficial and detrimental for the individual and the cooperation in the team. If a successfully implemented diversity management focuses age stereotypes, negative assumptions can be reduced and cooperation in mixed-age teams can be considered beneficial. Diversity management as measures against age stereotypes and for mutual acceptance and understanding should include staff from various hierarchical levels of the inpatient setting.