The study aimed at The Effectiveness of using electronic educational games in developing Al- Azhar primary stage pupils'' English vocabulary skills. The participants of the study were (60) sixth year primary institute pupils from Efwa primary institute, Beni-suef. The study adopted the quasi-experimental research design. So, there were two groups: an experimental group (n= 30) and a control one (n= 30). To collect data, the researcher used multiple instruments: a diagnostic test, a pre/post test, a list of games, Skills of vocabulary and teachers' guide. The researcher taught both groups: the experimental group was taught through using electronic educational games while the control group was taught through the regular method of teaching. Analysis of the results revealed that the experimental group participants achieved a significantly higher level in their English vocabulary skills than those of the control group. Thus, there was a statistically significant difference between the mean scores of experimental group in pre-t and post- test of vocabulary in the favor of the post-test. The effect size of using electronic educational games strategy was found to be high. The study recommends using electronic educational games in developing English vocabulary skills.