Academic failure among students is influenced by many factors. One of these important factors is undesirable attributions and locus of control. Attribution styles and locus of control are the important factors affecting students' academic achievement and learning process, which have reciprocal relationship with their success and failure. The purpose of this research was to recognize attribution styles among students in Agriculture College of Shiraz University and to investigate the relationship between attribution styles, locus of control and academic achievement. Multi-stage stratified random sampling was used to collect data from 300 students. The findings indicate significant relationship between attribution styles and academic achievement. So that, a positive significant relationship was found between attributions of successes to internal, persistent and general factors and academic achievement, and a negative significant relationship was found between attributions of failures to external, unstable, and specific factors and academic achievement. The results also revealed a significant difference between explanatory style of junior and senior students, so that attributions of the junior students for positive events were more external, unstable and specific and for negative or undesirable events was more internal, stable, and general in comparison with senior students. In the end, some suggestions have been presented for reforming attribution programs in universities and changing undesirable attributions of students.