The objectives of this study were to identify students' anxiety levels and to investigate the relationship between students' speaking anxiety and their speaking ability in EFL classes. This study is quantitative research in the form of correlation research. The participants were 30 eleventh-grade students at one of senior high school in Yogyakarta. The data were collected using a questionnaire and a speaking test. The questionnaire was employed to assess the student's level of anxiety, while the speaking test was utilized to gauge the extent of their speaking proficiency in the EFL lesson. In addition, the researcher employed SPSS 27 to examine the correlation between students' anxiety levels and speaking proficiency.The results of the questionnaire showed that most students have a high level of anxiety when speaking in the EFL Classroom. Some factors that cause students' anxiety when speaking English in EFL classes are lack of confidence, shyness, fear of speaking inaccurately and fear of negative evaluation. Furthermore, the result of the hypothesis test showed that the significant value is 0.025. It showed that the significance value is lower than 0.05. It can be said that Ha is accepted where there is a relationship between students' anxiety level and their speaking ability. The relationship between the two variables is a negative relationship with a Pearson Correlation coefficient value of -409. It indicated that when students have a high speaking score, their anxiety level will be low. Conversely, if students have a low speaking score, it shows that they have a high level of anxiety. Moreover, the strength of the relationship between variable x and variable y is a moderate correlation because it has a coefficient value of 0.409, which is between 0.40 - 0.59.