Background Evidence-based practice (EBP) is an important competency of undergraduate nursing students which should be cultivated before graduation by increasing future healthcare providers' knowledge, skills and attitudes towards EBP. This study aimed to describe nursing students' competencies (attitudes, knowledge, skills) in Evidence-based practice (EBP) and to determine factors predicting EBP competency. Methods A descriptive cross-sectional study was conducted at the Higher School of Health Sciences and Techniques of Sousse (Tunisia) among 365 nursing students. Data were collected using the validated Evidence Based Practice Competencies Questionnaire (EBP-COQ). Multiple linear regression was performed to determine factors predicting EBP competencies. Results The overall score of EBP-COQ questionnaire was 3.26 +/- 0.53 out of 5. The attitude, skills and knowledge subscales received 4.04 +/- 0.41; 3.05 +/- 0.77 and 2.70 +/- 0.74 as mean scores respectively. Multiple linear regression analysis (table 4) revealed that significant related factors were academic level (beta = 0.271, p = 0.001), English-language reading skills (beta = 0.435, p < 0.001), facing staff resistance in implementing a new evidence-based procedure (beta = - 0.081, p = 0.035) difficulties in obtaining full-text papers (beta = - 0.127, p < 0.001) and training in methodology (beta = 0.232, p < 0.001) and also in statistics (beta = 0.205, p < 0.001). Conclusions These results help to understand students' attitudes, knowledge and skills in EBP and can be therefore a starting point to develop effective strategies for EBP curricula.