We conduct an explorative study to investigate the effect of subjectivity in performance evaluation practices on managerial motivation in public sector organisations. Increased subjectivity can enhance motivation if supervisors are able to provide better informational feedback. However, subjectivity is likely to reduce motivation if it reduces perceived mission clarity or negatively affects relations between supervisors and subordinates. Our analysis is based on a survey among 94 public sector managers in the Netherlands. We predict and find that subjectivity in performance evaluation practices reduces perceived mission clarity, which in turn decreases motivation. We also find that subjectivity negatively affects subordinate managers¿ trust in their supervisor, which also reduces motivation. Jointly, these results indicate that the negative effects of subjectivity in performance evaluation practices outweigh its potential positive consequences, suggesting that New Public Management's focus on more objective performance measures can indeed be beneficial. By itself, however, this does not automatically imply that more objective systems in general are optimal in all public sector organisations as such systems may have dysfunctional side effects such as distortion of performance measures, gaming or manipulation. In addition, we find that the effects of subjectivity are moderated by organisational characteristics.