Fatigue characteristics of flyash compacts are studied within the framework of fracture mechanics. Also, a test method is proposed to investigate the fatigue behaviour of flyash compacts. The curves of stress versus number of cycles to failure for flyash with moisture contents of 0.1% and 0.3% indicate that flyash compacts possess fatigue characteristics. The da/dN-DELTAK and a-N relationships have been deduced for moisture content 0.1% from the principles of fatigue crack growth. The results show that the rate of fatigue crack growth in flyash compacts obeys the Paris power law equation, and the fatigue properties of flyash compacts can be characterised as falling between those of metals and ceramics.