The main Serbian TIMSS 2003 results showed that (a) mathematics achievement of the Serbian students, expressed by average percent correct on all test items, was 41, being equal to the international average; (b) the best achievement of the Serbian students was found for tasks on algebra, whereas the poorest achievement was obtained for tasks on data; and (c) while 21% of the Serbian students had reached the high TIMSS 2003 international benchmark, 20% of themhad not attained basic mathematical knowledge and skills. These results were examined the light of the TIMSS 2003 results of other economically and educationally similar entities as well as the results of relevant educational studies realized in Serbia in last twenty years. The article also gives a direction for improvements of the Serbian mathematics education supported by the Serbian TIMSS 2003 results.