Critical thinking and clinical decision-making are crucial competencies in nursing practice. Concept mapping, a modern and constructive educational technology, promotes deep and meaningful learning. This study aims to determine the impact of concept mapping program on the critical thinking and clinical decision-making of Neonatal Intensive Care Unit (NICU) nurses.This semi-experimental study was conducted on nurses working in the NICU of Vali-Asr Hospital in Birjand, Iran from September 2013 to January 2014. Nurses who had bachelor degree in nursing were selected to take part in the study and nurses who missed two consecutive training sessions were excluded from the study. Over five consecutive weeks, 30 NICU nurseswho had been selected by convenience sampling underwent training using concept maps covering five NICU scenarios. Data were collected before and after the intervention using a three-part questionnaire that included a demographic information form, the California critical thinking skills test - form B, and clinical decision-making cards with the Q-Sort method. Statistical analysis (version 16) was performed using paired and independent t-tests at the significance level of P<0.05.The mean scores of critical thinking and clinical decision-making significantly improved after the intervention, rising from 12.6±3.3 and 84.3±4.9 before the intervention to 26±5.1 and 98.2±1.9 after the intervention, respectively (P<0.001). The increase in clinical decision-making score was notably higher among nurses who were not officially recruited compared to those who were (P<0.001). Additionally, nurses with less than 10 years of work experience obtained higher score of decision-making compared to those with longer experience (P<0.001).Incorporating concept mapping into nursing education can significantly enhance critical thinking and decision-making skills of NICU nurses. Hence, this method is recommended for use in clinical nursing education programs.