The objective of this research was to get empirical evidence whether or not there is a relationship between vocabulary mastery and reading comprehension of the tenth grade students of SMAN 5 Tangerang in the 2006/2007 academic year. The method used in this research was a survey that involved a correlational technique. The population of this research was 139 students distributed into four classes, while the sample was 40 students. The data were collected by giving two tests for the students; they were vocabulary and reading comprehension tests. In data processing, the formula of Pearson?s Product Moment was used after testing the normality of data distribution and the linearity. Based on the result of data analysis, it is known that the score of r-observed (0.571) is higher than the r-table at 0,05 level of significance (0,312). The working hypothesis (Hi) is accepted, while null hypothesis (H0) is rejected. Therefore, the relationship between vocabulary mastery and reading comprehension is in level of significance.