This research deals with the effect of critical reading on English vocabulary enhancement.The objectives of this research areto see the students’ English vocabulary mastery before critical reading, to see the students’ English vocabulary mastery after critical reading, and to see whether there is a significant difference between before and after critical reading to enhance students’ vocabulary mastery. The research method used was a quasi-experimental research design. The subjects of this study are26 students of theeleventh-grade Nursing Assistant students of SMK Kesehatan Samarinda in the academic year 2021/2022, and the samples amountof.The design used was pre and post test design. The research results showed that the students’ vocabulary mastery before having critical reading falls in the fair category. Whereas after having critical reading, the students’ vocabulary masteryfalls in the goodcategory. After hypotehesis testing, it is found that thet-test value is higher than the value of t table.It means the alternative hypothesis (Ha) is accepted, while the null hypothesis (H0) is rejected. This shows there is a significant difference between before and after having critical reading on students’ vocabulary mastery of the eleventh-grade students at SMK Kesehatan Samarinda in academic years 2021/2022. Therefore, it can be concluded that teaching vocabulary through critical reading gave a better result in improving students’ vocabulary mastery.It is suggested that teachers who want to improve students’ English vocabulary can apply critical reading in reading texts. It helps students to explore the words used in reading texts.