Stanislaw Antoni Szczuka (about 1654-1710) appeared frequently in sources for the reign of Jan III Sobieski and the beginnings of the reign of King Augustus II. The author presents his career from the time he assumed the office of the Crown Referendary in 1688 to his transference to the office of Vice-Chancellor of the Grand Duchy of Lithuania (1699). The competence of the office of a referendary who, for all practical purposes, fulfilled court functions, was not distinctly defined in the legislature of the Commonwealth. One could have expected that Szczuka's copious correspondence from the period when he held this post would contribute to its further characterisation. The authors of the letters, written in 1688-1699, were numerous representatives of the prosperous middle gentry and magnates. The letters concerned primarily requests for royal privileges relating to public offices, and sometimes for other forms of benefiting from state revenues. Upon certain occasions, they promised both him and the king (sometimes also the queen) suitable 'fees', whose level depended on the rank of the desired office. The letters almost never mention problems associated with holding the office of a referendary. The poll conducted upon the basis of the letters addressed to Szczuka at the time when he was a regent of the Crown Chancery (1684-1688) made it possible to ascertain that his correspondents were representatives of the same environments and sometimes the same people who later on wrote to him in his capacity as a referendary. The topics of the letters are identical, the only difference being that Szczuka received many more letters as a regent of the Crown Chancery than as a referendary. The reason probably lay in the fact that as the chancery regent he enjoyed direct impact upon the editing and rate of issuing documents. Hence, his protection was much more important for the interested parties than the influence of his formal superiors. All authors dealing with Szczuka's public career stress the part played by the favours of King Jan Sobieski, certainly at the beginning of the career. At the time of Augustus II the number of petitioners writing to Szczuka diminished only slightly. Finally, it must be added that the letters addressed to Szczuka constitute a rich source for learning about the mechanisms which shaped his public career. At the same time, they indicate that the competence of the referendary office played a secondary role, and that the discussed letters do not enhance our knowledge about its functioning.