Aims: Preparation of nurses plays an important role in nuclear events and reduces the nuclear consequences. Training is an important part of preparation process which is provided in various ways. This research was done to examine the efficacy of nuclear nursing care training by multimedia software on cognitive learning levels. Methods: In this quasi-experimental study, 30 nurses of one of hospitals in the country were selected by purposive sampling in year 2009.A Multiple choice researcher-designed questionnaire with 30 questions about three levels of cognitive learning including knowledge, comprehension and application was prepared and the testwas done in three stages before, immediately after and 4 weeks after nuclear nursing care training by multimedia software. Scores were compared by repeated measure ANOVA test using SPSS17. Results: Knowledge scores’ mean in three stages, before, immediately after training and after four weeks were 4.5±1.5, 7.43±1.7, 7.6±1.7, respectively and comprehensive scores’ mean were 3.93±2.05, 8.73±2.03, 7.93±2.3, respectively and application scores’ mean were 2.72±1.53, 7.4±1.5, 6.4±2.1, respectively. The average total scores were 10.73±4.02, 23.5±4.25, 21.8±4.96, respectively and showed a significant difference for all stages and at all levels of learning (p<0.001). Conclusion: Results prove that multimedia software is effective; therefore, nuclear nursing care training by multimedia software can be a good alternative to other methods.