The actuator disc model is applied on lattice-type meteorological masts to estimate the influence of the tower on the accuracy of the measured wind speed. Combining the results with corrections for the boom, on which the anemometer is mounted, good agreement is found for measurements made on the mast at Tjaereborg. Iso-speed plots are computed to estimate the influence of different solidities. Depending on the distance from the mast and the solidity the influence from a typical mast is normally less than 3%.