Concrete bricks are building materials composed of cement, water, and aggregate (sand). The concrete bricks composition consists of materials easily obtained by the public. There are several materials, having the same characteristics with concrete bricks materials, considered as waste by the people. The research aims to identify the concrete bricks compressive strength with the addition of fly ash with a mixture variation of 2.5%, 5%, 7.5%, and 10% on the cement weight. This research is an experimental research using cube shaped-specimens with a length of 8 cm and a width of 8 cm. The specimens for each variation consist of 3 concrete bricks specimens. The test for concrete brick compressive strength was conducted on the age of 28 days. The average value of the test shows that: a) the average compressive strength of 2.5% fly ash variation is 56.8 kg/cm2, b) the average compressive strength of 5% fly ash variation is 54.1 kg/cm2, c) ) the average compressive strength of 7.5% fly ash variation is 78 kg/cm2, d) ) the average compressive strength of 10% fly ash variation is 80.6 kg/cm2. Each compressive strength meets I and II Metu requirement.