Purpose: This study aims to investigate quality of feedback as offered by supervisor-assessors with varying levels of assessor expertise following assessment of performance in residency training in a health care setting. It furthermore investigates if and how different levels of assessor expertise influence feedback characteristics. Design/methodology/approach: Experienced (n = 18) and non-experienced (n = 16) supervisor-assessors with different levels of assessor expertise in general practice (GP) watched two videotapes, each presenting a trainee in a "real-life" patient encounter. After watching each videotape, participants documented performance ratings, wrote down narrative feedback comments and verbalized their feedback. Deductive content analysis of feedback protocols was used to explore quality of feedback. Between-group differences were assessed using qualitative-based quantitative analysis of feedback data. Findings: Overall, specificity and usefulness of both written and verbal feedback was limited. Differences in assessor expertise did not seem to affect feedback quality. Research limitations/implications: Results of the study are limited to a specific setting (GP) and assessment context. Further study in other settings and larger sample sizes may contribute to better understanding of the relation between assessor characteristics and feedback quality. Practical implications: Findings suggest that even with supervisor-assessors with varying levels of assessor expertise who are trained in performance assessment and the provision of performance feedback, high-quality feedback is not self-evident; coaching "on the job" of feedback providers and continuous evaluation of feedback processes in performance management systems is crucial. Instruments should facilitate provision of meaningful feedback in writing. Originality/value: The paper investigates quality of feedback immediately following assessment of performance, and links feedback quality to assessor expertise. Findings can contribute to improvement of performance management systems and assessments for developmental purposes. (Contains 2 tables and 2 figures.)