This article deals with the impact of lateral refraction on the measurement of horizontal directions. The measurement of lateral refraction under different conditions is presented. A car was used as a source of lateral refraction. Horizontal angle measurements were made when the car was at different distances from the instrument. The results of the measurements were compared with the results calculated using the equations from the literature, taking into account the same conditions as were in the measurements.

Key words: lateral refraction, angle of refraction, temperature gradient