This study attempted to investigate the relationship between ESL learners' Oral proficiency and their level of Self-esteem. The sample consisted of 30 students of Master studying English language at SBK Women's University Quetta Baluchistan. The data were gathered through two instruments: Rubric for ESL Oral Proficiency along with voice recording and the Rosenberg (1965) Self-esteem Scale. The technique applied was non participant controlled observation. To determine the relationship between ESL learners' Oral proficiency and their level of Self-esteem, correlational analysis was employed quantitatively. The findings revealed a significant positive relationship between the two variables and asserted Krashen's Affective Filter Hypothesis that an imaginary barrier of affective factors in learner prevents the learner from acquiring the target language.