This report presents the results from the research project “Rapid assessment of reinforcement corrosion in concrete bridges”. In this project the effect of moisture in concrete on the measurement of corrosion by the RapiCor was studied in the laboratory. The RapiCor technique was used on over 20 real bridge concrete structures in order to evaluate its applicability for assessment of corrosion conditions of reinforcement steel in real bridge concrete structures. The results measured by the RapiCor from 13 bridge structures are presented in this report. From the laboratory study conclusions can be drawn that wettingdrying cycles apparently affect the resistivity of concrete and half-cell potential of steel, but not significantly affect the corrosion rate, if the corrosion rate is in the range of moderate to high corrosion. From the field evaluation the conclusions include that the RapiCor can in general be effectively used in assessment of corrosion conditions of reinforcement steel in bridge concrete structures with satisfactory precision, and that the weather will not significantly affect the assessment of corrosion conditions by the RapiCor technique. Based on the conclusions some suggestions are given for proper use of the RapiCor technique in assessment of corrosion conditions of reinforcement steel in the bridge concrete structures.