Introduction: Collaborative testing is a learning strategy thatprovides students with the opportunity to learn and practicecollaboration. This study aimed to determine the effect ofcollaborative testing on test performance and retention of coursecontent in nursing students of Shiraz University of MedicalSciences, Shiraz, Iran.Methods: This quasi-experimental study was carried out on 84students enrolled in the course of Medical-Surgical 2 in Spring2013 and Fall 2013 semesters. The control group consisting of 39students participated in the first mid-term exam in an individualformat. The intervention group, on the other hand, consisted of45 students who took the test in a two-stage process. The firststage included an individual testing, while the second stage wasa collaborative one given in groups of five individuals chosenrandomly. Four weeks later, in order to investigate retention ofthe course content, both groups took part in the second mid-termexam held individually.Results: The study findings showed significant differencebetween the mean scores in the intervention group in the Fall 2013semester (p=0.001). Besides, a statistically significant differencewas found between the two groups regarding the tests mean scores(p=0.001). Moreover, retention of course content improved in thecollaborative group (p=0.001).Conclusion: The results indicated an increase in test performanceand a long-term learning enhancement in collaborative testingcompared with the traditional method. Collaborative testing, as anactive learning technique and a valuable assessment method, canhelp nursing instructors provide the alumni with strong problemsolvingand critical thinking abilities at healthcare environments.Keywords: Collaborative; Nursing Education; Collaborative learning