['Peer review is the gold standard for evaluating scientific quality. Compared with studies on inter-reviewer variability, research on panel evaluation is scarce. To appraise the reliability of panel evaluations in grant review, we compared scores by two expert panels reviewing the same grant proposals. Our main interest was to evaluate whether panel discussion improves reliability.', "Thirty reviewers were randomly allocated to one of the two panels. Sixty-five grant proposals in the fields of clinical medicine and epidemiology were reviewed by both panels. All reviewers received 5-12 proposals. Each proposal was evaluated by two reviewers, using a six-point scale. The reliability of reviewer and panel scores was evaluated using Cohen's kappa with linear weighting. In addition, reliability was also evaluated for the panel mean scores (mean of reviewer scores was used as panel score).", 'The proportion of large differences (at least two points) was 40% for reviewers in panel A, 36% for reviewers in panel B, 26% for the panel discussion scores, and 14% when the means of the two reviewer scores were used. The kappa for panel score after discussion was 0.23 (95% confidence interval: 0.08, 0.39). By using the mean of the reviewer scores, the panel coefficient was similarly 0.23 (0.00, 0.46).'] Does panel discussion improve reliability of peer review for medical research grant proposals?