The effect of partial replacement of cement by unprocessed calcareous fly ash on fresh and hardened properties of self-compacting concrete was investigated. Concrete mixes containing 27.5%, 35%, 42.5%, 50%, 57.5% and 65% of fly ash based on the total weight of binder (cement + fly ash) were tested. All the mixes were designed to have the same volume proportions of paste, fine aggregate and coarse aggregate. Properties investigated were slump flow, J-ring, V-funnel, L-box and sieve segregation of fresh concrete mixes and compressive and flexural strength, dynamic modulus of elasticity, water absorption, volume of permeable voids and density of hardened concrete. The results showed that increase in fly ash content from 27.5% to 50% leads to improvement in workability without significant effect on segregation resistance and hardened concrete properties. Further increase in fly ash content results in worsening of both fresh and hardened concrete properties.