The purpose of this study is to examine the relationship between the amount of time spent on homework in all subjects (HTAS), the time spent on mathematics homework (MHT), confidence in doing mathematics homework (HCM) and the mathematics achievement of students in Turkey, based on data from the programme for international student assessment (PISA, 2003). According to the results of the multiple regression analysis, the positive variable which best predicts mathematics achievement is the students' HCM. The next best variable for predicting mathematics achievement is a negative one, which is MHT. There is no significant relationship between HTAS and mathematics achievement. The negative relationship between MHT and mathematics achievement can be explained by the fact that, in Turkey, the same amount of homework is given to all students, without taking their individual differences into account. (Contains 4 tables.)