In this study, Turkish primary students' (sixth to eighth grade) motivation toward science learning was investigated and factors affecting this determined. The sample for the study consisted of 376 students from 5 different primary schools in Izmir. The data were collected through a Students' Motivation toward Science Learning (SMTSL) questionnaire which was developed by Tuan, Chin & Shieh (2005) and adapted for use in Turkey by Yulma & Cavas (2007). It was found that it was a valid and reliable tool for the Turkish students, having 6 sub-scales which were self-efficacy, science learning value, active learning strategies, performance goal, achievement goal, and learning environment stimulation. Also collected was data on students' science attitudes and achievement scores. Results showed that Turkish primary students' science motivation differed significantly in terms of their gender and grade level. Student's motivational level was found to have a considerable impact on their science attitudes and achievement in science. (Contains 7 tables.)