This paper presents an experimental study of the influence of two initial curing conditions, wet (fog room) and dry (65 RH and 20 °C), on the transport properties of fluid in normal concrete (100 OPC) and blended cement concrete (OPC/FA). After 28 days initial curing, concrete samples were dried at different relative humidities at 20 °C for about 12 weeks when the equilibrium moisture condition was achieved. Transport properties that include oxygen permeability, water permeability and oxygen diffusion were measured at the equilibrium condition of the samples, and total porosity and degree of saturation were also determined. The initial curing condition has significant effects on the transport properties; in particular the most prominent effects were observed on fly ash blended cement concrete, which performed extremely well when initially cured in wet conditions. © 2003 Elsevier Ltd. All rights reserved.