Background: Metacognition is a process that is at the top of all executive cognitive processes and key psychological factor that involved in decision making. Purpose: Examine the effect of metacognitive training program on staff nurses` decision making abilities. Method: A quasi-experimental (one group pretest/posttest) design was utilized. The study was conducted in Medical and surgical departments at Beni-Suef University Hospital. A simple random sample of 64 staff nurses was included. Metacognition Knowledge Questionnaire, Metacognitive Awareness Inventory and Decision Making Abilities Scale were used for data collection. Results:  Revealed that the majority 90.6% of staff nurses had unsatisfactory knowledge level at pre program which improved to 95.3% had a satisfactory knowledge post program and decreased to (78.1%) at follow up.. More than one third 42.2% of staff nurses had a moderate level of metacognitive awareness at pre program which improved to 87.5% had a high level post program and decreased to (81.3%) at follow up. About two thirds 64.1% of staff nurses had a moderate level of decision making abilities at pre program which improved to 93.7% had a high level post program and decreased to (92.2%) at follow up. Conclusion: The metacognitive training program had a greater effect on improving staff nurses` metacognitive knowledge and awareness that was reflected in their decision making abilities. Recommendations: Encourage staff nurses to implement metacognitive strategies that improve their abilities to make effective and sound decisions. Involve metacognition concept into nursing curricula and focus on its importance in different aspects of nursing profession.