This research was held to see the reliability of English Summative test for the first semester of the first year class students. This research was held in SMK Muhammadiyah 9 Cipulir, Jakarta Selatan in January, 2008. The writer took 38 students as the sample of the research. The research instruments are English Summative test of the first year class students and the parallel test and count reliability from scores of both test by using the equivalent froms method. From the research, the writer found that the English Summative test for the first semester of the first year class of the 2007/2008 academic year is reliable.