In this paper, hydro-abrasive erosion tests on plain concrete (PC) and on steel-fibre reinforced concrete (FRC) are performed, and the erosion behaviour of the materials for different erosion conditions is investigated. Effects of suspension velocity, impact angle and solid content have been studied in detail. Two major erosion modes are identified. When the impact angle is shallow (15degrees), the damage is caused mainly by cutting the cement matrix and exposing the aggregates. However, at orthogonal impact, the formation and development of fatigue cracks in the concrete is the main cause of erosion. The addition of steel fibres provides a reinforcement to improve the erosion resistance of hydraulic concrete at shallow impact angles (15degrees) only. For low suspension velocities (ca. 60 m/s), fibre reinforcement and solid abrasive content do not influence the erosion rate favourably. For higher suspension velocities, abrasive content becomes important. (C) 2002 Elsevier Science B.V. All rights reserved.