Background and Objective: The need for critical thinking in nursing has been accentuated in response to a rapidly changing health–care environment. Nurses must think critically to provide effective care while coping with the expansion in their role associated with the complexities of current health care systems. The aim of the study was to compare the critical thinking skills and critical thinking dispositions between the nursing students and clinical nurses of some selected educational hospitals of Zanjan University of Medical Sciences (ZUMS). Materials and Methods: This descriptive study was performed on 50 nursing student and 50 clinical nurses from some selected ZUMS educational hospitals through convenient sampling. The main study tools were the California critical thinking Skills Test (CCTST) and California critical thinking Dispositon Inventory (CCTDI). The data was analyzed by SPSS 16 software using the t-test and Pearson correlation coefficient. Results: The mean scores of the critical thinking skills for the nursing students vs. clinical nurses were 9.02 and 12.68, respectively, and the t-tests showed a significant difference between the two groups (P=0.002). By contrast, there was no significant difference in the mean critical thinking Dispositons scores (P=0.47). There was also not a significant relationship between the critical thinking skills and critical thinking dispositions scores in two groups (r=0.071). Conclusions: It seems that neither the critical thinking skills nor dispositions scores are desirable. Therefore, it seems necessary to consider a revision of the teaching strategy for promoting critical thinking skills in nursing plans.