Foundations on drilled piers are very efficient for carrying large loads to a deep bearing stratum. Pertinent data on the behaviour of such elements are quite rare due to the difficulties encountered with the large scale test programs. Field tests on 8 axially loaded drilled piers and 9 laterally loaded piers have been performed on 5 different sites in Romania. Behaviour under axial load was strongly affected by the nature of the soil at the base of the pier. Under lateral load, piers behaved satisfactorily, regardless of the direction of the load and the nature of the soil. Based on the interpretation of the results, analytical procedures were developed for defining the load-settlement and load-deflection relationship. For the covering abstract of the conference see IRRD 287689. (TRRL)