The aim of this study is to assess the factors that influence biology teacher candidates' levels of academic self-efficacy. This study, in which the descriptive model was used, was carried out with the participation of 155 biology teacher candidates. The data were collected through the Academic Self-Efficacy Scale and Personal Information Form. It was determined in the study that the biology teacher candidates' levels of academic self-efficacy are above the medium level, and a statistically significant difference exists between the levels of academic self-efficacy according to gender in favour of the male teacher candidates. In addition, a statistically significant difference was found between the levels of academic self-efficacy and grade levels; the level of academic self-efficacy increases as the grade level increases. It was also determined that the level of academic self-efficacy changes most under the influence of general academic achievement, and then under the influences of grade level and gender variables. © 2010 Elsevier Ltd. All rights reserved.