Nurse’s cognitive abilities, especially the ability to process information and make decisions on the patient's bedside, are key components. Hence, this study evaluated the effect of concept mapping on nursing students’ ability to make decisions. The quasi-experimental study with two groups design and pre-test and post-test was conducted in 2012. 32 numbers of 7th-Semester nursing students randomly were divided into control and experimental groups. At the first, experimental group was taught concept mapping within 8 hours, then the test group and the control group using concept maps and the usual method in clinical training during one month. Clinical decision making using clinical questionnaires before and after the intervention were determined. In addition, software SPSS, 19 version,was used for statistical analysis; the mean pre-test scores of the two groups showed no significant difference in clinical decision making ability (p=0.37); Consequently, clinical decision making ability in the test groups (168.53 ± 10.70) compared with controls (139.66 ± 15.90) indicated a significant increase (p = 0.02). Acording to the results, using concept mapping in nursing education can lead students to develop skills in clinical decision making, therefore, as one of the important missions of higher education would be considered.