Abstract: Self-compacting concrete (SCC) generally has higher powder content than normally vibrated concrete (NVC) and thus it is necessary to replace some of the cement by mineral admixtures such as flyash to achieve an economical and durable concrete. SCC contains a large mortar volume as compared to NVC. This work presents the influence of fine aggregate particle size and fly ash on the compressive strength of mortar for SCC. Mortar mixes consists of five different cement replacement percentage (CRP) by flyash are investigated for four different particle sizes of fine aggregate. The compressive strength of mortar cubes at the curing time of 7, 28 days was determined.