This work presents the results of an experimental study on surface damage due to erosion, corrosion and their interactive effect in sea water in the presence or absence of 1 g L 21 suspended nanosize as well as microsize Al 2 O 3 particles. Erosion and erosion-corrosion tests have been conducted on low carbon steel targets using a rotating cylinder system. It is found that nano-and microsize particles act as inhibitors and decrease the pure corrosion rate in comparison to base fluids free of these particles, but over time, the inhibitory effect of microparticles is lost. The presence of microparticles causes more severe steel erosion than sea water, whereas the difference between nanofluid and sea water is not significant. In spite of the effects of nanoparticles on pure corrosion and net erosion, mass loss due to erosion-corrosion in a nanofluid is much higher that the base fluid but is less than the fluid containing microsize particles. Rashidi et al. Erosion, corrosion and erosion-corrosion of carbon steel in nanofluid Tribology 2013 VOL 7 NO 3 Rashidi et al. Erosion, corrosion and erosion-corrosion of carbon steel in nanofluid Tribology 2013 VOL 7 NO 3