Since 1995, achievements in mathematics and science have been assessed worldwide every four years by TIMSS (Trends in International Mathematics and Science Study), whose outcomes have influenced the development and (re)design of mathematics and science education curricula in a number of countries. This paper examines how TIMSS has influenced changes in the mathematics curriculum in Serbia in primary education. The paper first briefly presents TIMSS results of Serbian students that call for curricular improvements. It then gives a summary of these changes regarding educational standards for the end of primary education. The paper ends with a critical examination of these standards and suggestions for their enhancement.