This article surveys the rise of the clinical laboratory in The Netherlands. By way of an introduction an overview is given ofthe development of medical diagnostics, especially the increase in diagnostic objects and the expansion of technical an chemical instrumentation. Both aspects considerably affected the rise of the clinical laboratory. More products which could be investigated without the presence of the patient, such as stomach contents, cerebro-spinal fluids and tissue samples, were obtained. The necessity of making provision for the installation of physical and chemical instruments, such as the microscope, balances, colorimeter, centrifuge, etc., gave an increased impetus to the development of laboratory facilities. The development of this process in The Netherlands is explored firstly by searching through the Dutch medical literature for publications on the subject of medical laboratory work. Secondly, inventories were made for the laboratories which were mentioned in the medical yearbooks of The Netherlands. Most ofthe Dutch literature consisted of translations of English and German books on diagnostics, and it is only around 1900 that the first original publications can be located. The list of laboratories mentioned in the records makes it clear that the growing need for clinical laboratory procedures was first responded to by chemists and apothecaries, who recognised that clinical chemistry offered new money-making possibilities. It is difficult to judge the extent to which the general practitioner obtained facilities for clinical research within his home. Catalogues of medical instruments illustrate only what was obtainable. Financial and emotional (accentuation of the gap between technical an clinical types of work) barriers, and the restrictions imposed by education and by the possibilities for post-graduate education in the new techniques of clinical research all made a rift between the theory and praxis of physical and chemical diagnosis. Regarding hospital laboratories, there was a clear difference between teaching and other hospitals. In the first the emergence of the laboratory took place in relation to the founding of teaching and research facilities. In the latter clinical chemistry was taken up by hospital physicians working together with hospital pharmacists. Finally, an attempt has been made to reconstruct changes within the medical profession by recording the first physicians to specialize in clinical laboratory work and by pointing to the emergence of a group of para-medical personnel. From the above, it can be established that the period before 1925 was a preformative period, and that the establishment of clinical laboratories in The Netherlands as an integral part of health care dates only from the late 1930'sand 1940's.