this study sought to examine the effect of cooperative game on iranian students achievements in english alphabet learning. cooperative games are games, in which players or teams work together towards a common goal without defeating someone. the methodology used in this study was experimental. the population of the study was 60 female students from the grade one in secondary school in tabriz, iran. prior to study five grade one classes were administered a homogeneity test .from the results obtained through the test, two homogenous groups were selected as an experimental and control group. the tools used were a homogeneity test, an achievement test, two oral tests and six practice quizzes. cooperative game was used with a grade one class and was compared to another grade one class which worked in groups lacking the game. both groups completed homogeneity test, six practice quizzes and two oral tests which measured changes in academic scores. the study suggested the following null hypothesis: h0.cooperative game has no significant effect on iranian students achievements in english alphabet learning. the findings of the achievement test are analyzed through t-test. the results of the study suggest that cooperative game had a significant effect on iranian students achievements in english alphabet learning.