The study aimed at the effects of grammar on learner’s academic performance in English subject in secondary schools in Uganda with a case of Luwero district and it was guided by the following objectives; To examine the relationship between the use of grammar learning strategies and student achievement in English subject, to evaluate the effect of grammar on student writing skills and to establish the effects of grammar on student’s attitude towards English subject. Keeping other factors constant, a percent increase in the use of grammar learning strategies would on average lead to 0.758 percent increase in student’s achievement in English subject. This is statistically insignificant at 95% confidence interval since the P-value (0.067) is greater than 0.05 level of significance and therefore we accept the null hypothesis and conclude that that there is no relationship between the use of grammar learning strategies and student’s achievement in English subject. The Rsquared (0.627) is greater than the adjusted R-squared value (0.568) because it imposes a harsher penalty on the linear regression model. And hence a good fit. Teachers should emphasize the use of English modeling approach in their word problem content, to change pedagogy and to provide assessment that focuses more on understanding than on mastery of language. Students need more time to understand grammar word problem concepts, and this study was unable to correctly answer some of the questions because they required a deeper level of understanding.