This paper considers the main results and some educational implications of the TIMSS 2003 assessment conducted in Serbia, in the fields of mathematics achievement of Serbian eighth grade students and the mathematics curriculum context of their achievement. It was confirmed that Serbian eighth graders have made average scale score of 477 points, and with this achievement they are placed in the zone of intermediate international benchmarking level. The average mathematics achievement of the Serbian eighth graders is somewhat above the average international mathematics achievement. The best result was achieved in the content domain of "algebra", and the lower result in the content domains of "measurement" and "data". In the defined cognitive domains the Serbian students have achieved the best results in "solving routine problems" and "knowing facts and procedures", and the weaker result in "reasoning". Statistically significant difference was found in the mathematics achievement between girls and boys in the Serbian TIMSS 2003 sample, so the girls’ average scale score was 480 points and the same value for the boys was 473 points. The achieved results raise many questions about the contents of mathematics curriculum in Serbia, its quality and basic characteristics of its implementation. These results can be eligibly used to improve the mathematics curriculum and teaching in Serbian primary school.