Background & Objectives: One the most undeniable ways in improving education quality is lesson planning and having a lesson plan. Lesson planning is a process for determining appropriate educational objectives, identifying problems, needs, facilities, and limitations which may present in achieving educational objectives. The aim of this study was to determine the knowledge and attitude of the instructors in Ardabil University of Medical Sciences about lesson planning. Methods: Samples included all the instructors working in Ardabil University of Medical Sciences. The instrument for data collection was a researcher made questionnaire whose dependability was confirmed by some instructors at the University and its reliability was 0.75 (Alpha cronbach test). The data were gathered through completing the questionnaire by instructors. The data were analyzed using SPSS 15 by Pearson correlation, one-factor variance analysis, Tukey and T-test. Results: The majority of 81 instructors participated in the study (76.5%) were male. Most of them were specialists or sub specialists. The mean score for knowledge was evaluated as below average (17.18±4.18) and for attitude as good (39.37±9.7). The results showed a significant difference in the mean of knowledge score and the mean of attitude score. Moreover, mean knowledge on course objectives writing showed significant difference between genders. Conclusion: Considering the importance of lesson planning in improving the educational objectives, it is necessary to pay more attention, do more studies in order to find out the factors affecting instructors lesson planning.