Abstract In the frame of its researches concerning GPS positioning the Universidad Publica de Navarra has carried out in 2003 a study to know the possibilities of this positioning technique for monitoring building's displacements. A 30 m concrete building was monitored for several months by observations from a geodetic micronetwork placed around. During the observation period the computed variations in position have standard deviations of 3.1 mm in the XX -axis, 6.6 mm in the YY -axis and 9.1 mm in the ZZ -axis. These values reveal that the building displacements are very small and that they are masked by the characteristic errors of GPS observations. The correlation between the observed displacements and the weather variables was analyzed and only temperature and direct radiation were significant, but the relationship was weak, with low values of the correlation coefficients r. In the visual analysis of the coordinate variations we observed that the building suffers a negative displacement with respect to the XX -axis in the morning up to noon, when the displacements become positive, with an observed variation over the reference position of ±2 mm. With respect to the YY -axis, the building remains fairly stable until afternoon, in which it moves north approximately 2 mm in relation to the reference position. With respect to the ZZ -axis, we observed an increase of the height of the building during the central hours of the day of around 1 cm. These displacements observed in the building agree qualitatively with the a priori expected displacements as a function of the movement of the sun throughout the day.