The analysis presented in this paper deals with the accuracy of a weigh-in-motion (WIM) system installed on Trans-Canada Highway west of Regina. Spot speed data collected by the WIM system are compared with the measurements taken by a radar meter; the WIM data on axle spacing are compared with data obtained by manual measurements; and the dynamic weight data gathered by the WIM system are evaluated against static weights. The following conclusions can be made from this study: The WIM system under investigation provides accurate data for spot speed and axle spacing. The study data for 88 trucks indicate that the dynamic weights recorded by the WIM system may contain high magnitudes of both systematic and random errors. However, the results of analysis presented indicate that a proper calibration of the system can reduce the systematic errors to a large extent and produce results that may be satisfactory for a number of highway planning and design functions. Key words: axle spacing, dynamic weight, highways, static weight, traffic studies.