Background: Research has shown that narrative feedback, (self) reflections and a plan to undertake and evaluate improvements are key factors for effective feedback on clinical performance. We investigated the quantity of narrative comments comprising feedback (by trainers), self-reflections (by trainees) and action plans (by trainer and trainee) entered on a mini-CEX form that was modified for use in general practice training and to encourage trainers and trainees to provide narrative comments. In view of the importance of specificity as an indicator of feedback quality, we additionally examined the specificity of the comments. Method: We collected and analysed modified mini-CEX forms completed by GP trainers and trainees. Since each trainee has the same trainer for the duration of one year, we used trainer-trainee pairs as the unit of analysis. We determined for all forms the frequency of the different types of narrative comments and rated their specificity on a three-point scale: specific, moderately specific, not specific. Specificity was compared between trainee-trainer pairs. Results: We collected 485 completed modified mini-CEX forms from 54 trainees (mean of 8.8 forms per trainee; range 1-23; SD 5.6). Trainer feedback was more frequently provided than trainee self-reflections, and action plans were very rare. The comments were generally specific, but showed large differences between trainee-trainer pairs. Conclusion: The frequency of self-reflection and action plans varied, all comments were generally specific and there were substantial and consistent differences between trainee-trainer pairs in the specificity of comments. We therefore conclude that feedback is not so much determined by the instrument as by the users. Interventions to improve the educational effects of the feedback procedure should therefore focus more on the users than on the instruments.