The debate on the effect of students’ homework time on their academic achievement has been extensively discussed; nevertheless, international research does not seem to have reach to any definitive result. This homework time subject is studied in this research for primary education students of 24 countries, using student fixed effects within-students between-subjects. For the countries under analysis our results show that homework time does not seem to affect the academic achievement of primary education students, and these results hold after many robustness checks. The policy implications derived from this analysis show that the current particularities of homework have to be improved for the countries under analysis to help students make a better use of their time.