The purpose of this paper is to estimate a set of marginal costs for road maintenance and operation. We use a panel data on a low level of aggregation. The data includes all costs for maintenance and operation on the Swedish National road network, 1998-2002. Using this data set we estimate cost functions and derive cost elasticities and marginal costs estimates. We find the mean elasticity of maintenance costs to be significant and in the range 0.57 ? 0.72 depending on cost category. We use these estimates to compute marginal costs as well. We find MC for paved roads to be 0.30 SEK per heavy vehicle kilometre. For gravel roads the corresponding number is 2.21. A MC for all roads, independent of pavement type, is estimated to 0.38 SEK per heavy vehicle kilometre. Focusing on operation, elasticities are not found to be significantly different from zero. This indicates that the cost of operation measures are unrelated to traffic and that marginal costs are zero.