Appropriate compaction is essential in producing roller-compacted concrete (RCC). An experimental program was conducted to study the effect of compaction on the strength and den-sity of RCC specimens. Compaction was achieved by tamping the sample with a hammer similar to that of ASTM D 1557. The main variables were the magnitude of compaction energy, number of lay-ers per mold, and cement content. The compaction energy ranged from 300 to 2700 kN-m/m³. The test results show that the decrease of the unit weight by 7.7% decreases the compressive and splitting tensile strengths by 73 and 71%, respectively. Increasing the cement content compensates for the reduction in compaction energy. The average degree of compaction of the cores taken from the field RCC test slabs was 99% of the unit weight of field samples prepared with a 2700 kN-m/m³ compaction energy.