The present study investigated the relationship between language learning strategy use, learning styles, gender, and second language (L2) achievement of Iranian English for academic purposes (EAP) learners. To this end, 120 Iranian EAP learners majoring in various fields of humanities including political sciences, psychology, economics and law participated in the study by completing Oxford's (1990) "Strategy Inventory for Language Learning" (SILL), and an adapted version of the "Perceptual Learning Style Preference Questionnaire" (PLSPQ) originally developed by Reid (1987). The results obtained from three separate Pearson product moment correlations indicated that there was a significant positive correlation between (a) language learning strategy use and L2 achievement; (b) learning styles and L2 achievement; and (c) learning styles and strategy use by Iranian EAP learners. Moreover, the results of multiple regression analysis demonstrated that both learning styles and language learning strategy use were significant predictors of the participants' L2 achievement; however, learning styles were found to be a stronger predictor. Also, the findings of two separate multiple regression analyses indicated that among the components of learning styles and language learning strategies, visual learning style and cognitive strategy use were stronger predictors of L2 achievement respectively. In addition, the results of an independent samples t-test showed cognitive and metacognitive strategies were the most frequently used strategy groups by females and males respectively. The results of another independent samples ttest indicated that group and visual learning styles were the most preferred types adopted by the female and male learners respectively.