Purpose The purpose of this paper is to provide a comprehensive meta-analytic examination of the relationship between employee age and customer mistreatment. Drawing on socioemotional selectivity theory and taking the cross-cultural and cross-sectoral differences into account and making the country-level and occupation-level comparisons possible for uncovering when age matters, the role of employee age on decreasing customer mistreatment is examined. Design/methodology/approach The data comprises of 103 independent samples collected from 48,067 frontline employees. Random effects individual correction meta-analysis procedure is used to aggregate correlation coefficients and correct them for sampling, measurement and range restriction errors. Meta-regression is used for examining the impact of key moderators. Findings Results consistently show that frontline employee exposure to customer mistreatment is decreased with age. Regarding national differences, negative associations are stronger in low power distance countries. Age has more potential to provide high-quality relations with customers in healthcare, banking, compared to call centers and hospitality sectors. Practical implications Healthy customer relations with fewer customer mistreatments come with employee age. However, results warn service managers about cultural and industry-related boundary conditions such as power distance and service orientation expectations. Originality/value This study is the first meta-analysis on the relationship between two contemporary challenges in organizational frontlines: the aging workforce and customer mistreatment. By conducting comprehensive data collection and analyses, this study concludes that older employees, especially in low power distance cultures, bring wisdom to service environments.