Nursing students have traditionally experienced difficulties with the science subjects in nursing curricula, and irrespective of the institution conducting a nursing programme, this trend appears to be continuing. A satisfactory means of predicting academic performance in these subjects will facilitate the development of educational strategies designed to assist students overcome their difficulties. In this study, an instrument called the Self-Efficacy for Science (SEFS) was developed and tested. The SEFS was designed to predict academic performance in the science areas of a first-year undergraduate nursing course. A cohort of first-year students enrolled in a bachelor of nursing course were surveyed by questionnaire. Students’ academic scores for two first-year science subjects were obtained and used as the criterion measure for the study. Principal component factor analysis revealed the SEFS contained six instead of the hypothesized four factors. These six factors could explain 70% of students’ self-efficacy for science. Cronbach alpha of the SEFS was 0·9. The SEFS could predict 24% of the cohort’s academic performance in a physical science subject and 18·5% for a bioscience subject. Studying science in the final year at high school was not statistically significantly related to the SEFS. Implications for students and future research are discussed.