This study was conducted to calculate the strength of brick materials that already mixed with fibers of coconut. Using coconut fiber mixture was aimed at producing a better composition of concrete. An experimental design was applied to the composition of cement, sand, water and coconut fiber with a ratio of 1 PC cement. It made the ratio was 4.5 PS sand. The strength testing or compressive strength after the materials have been dried as long as 28 days. The averaged at variation I (0%) of 1 kN / cm2, variation II (1.5%) of 0.498 kN / cm2, variation III (1.8%) of 0.441 kN / cm2 and variation IV (2.1%) of 0.379 kN / cm2 were done. It concluded the addition of coconut fiber with brick materials produced has a decreasing compressive strength value.