This paper examines the relationship between the academic self-efficacy of an adult learners group in an online learning context with their actual performance. Our study aims to evaluate the relationship between self-concept of a group of students in online context and their academic achievement. Data were collected from 63 students of both genders, with average age of 42 years old, selected from the first years of their undergraduate studies. We analyzed their performance in academic course specifies. An adapted questionnaire was used to measure self-efficacy (a=0.908). The data was analyzed using descriptive and inferential statistics. The Pearson correlation coefficient was used to see the relationship between self-efficacy and academic performance. The analysis of the data indicated that students' level of self-efficacy is high (average=45) and a significant relationship exists between self-efficacy and academic achievement (r=0.286, at 0.05 level).