This paper presents the results of Stefan Krukowski’s unknown and unpublished excavations, conducted in 1919–1923 at four cave sites located in the Sąspowska Valley (Ojców area, S Poland): the Koziarnia Cave, the Łokietka Cave (Fig. 1, 6), the Złodziejska Cave (Fig. 4) and the Tunel Stromy Cave (Sadlana) (Fig. 2). The knowledge we had thus far about S. Krukowski’s research in the so-called Jura Ojcowska was limited only to the information made available in his sparse publications. It was common knowledge that he had conducted excavations in 1918 and 1919 in the Ciemna Cave (Fig. 3), which had led to the discovery of a rich collection of Middle Palaeolithic artefacts. In its first part, this text is a critical review of the preserved sources of information on S. Krukowski’s research in the Sąspowska Valley. The second part constitutes an analysis of particular artefacts, such as a bone spoon found in the Łokietka Cave (Fig. 14) or a clay rattle from the Koziarnia Cave (Fig. 8). The first part discusses the field documentation preserved in the archives of the State Archaeological Museum in Warsaw, encompassing individual section drawings or plans of the particular sites and the few comments concerning his excavations to be found in the researcher’s journals. The detailed metric records handwritten by S. Krukowski, which accompany the artefacts kept in the State Archaeological Museum’s collections, have also been subjected to analysis. All the data have been compared so as to allow for as complete as possible a reconstruction of the location of S. Krukowski’s trenches and their stratigraphy, and – as a result – enabling the establishment of the find context of particular artefacts. In the case of the cave referred to in the metric records and section drawing as Sadlana cave (Fig. 2), it is possible to state with all certainty, based on the verification of the situation presented on the section drawing with the actual appearance of the cave in the Koziarnia Ravine, that S. Krukowski’s research encompassed the area of the lower entrance to the Tunel Stromy Cave (Fig. 10) and not the Sadlana Cave. The author uncovered a section 3.5 m thick at the site. It provided a small amount of flint artefacts, which were traces of Neolithic and Late Palaeolithic settlement, perhaps also Middle Palaeolithic (Fig. 11–13). In the Koziarnia Cave, S. Krukowski opened a trench located crosswise to the cave entrance, as a result of which he formed a transverse section located 4.5 m from the entrance (Fig. 1). Waldemar Chmielewski, who conducted excavations at this site in the late 1950s unaware of S. Krukowski’s earlier research there, located his trenches I and VIII at the exact same spot, and noted traces of S. Krukowski’s earlier trench (Fig. 6). A clay rattle with a broken handle, most probably to be linked with the Lusatian culture, was found in the top-most layers of the section, as were a few pottery sherds from the Roman and Medieval periods (Fig. 8, 9). In turn, in the lower layers, S. Krukowski found a Neolithic endscraper and three less characteristic flint artefacts (Fig. 7). In the case of two of these, their state of preservation (the postpositioned worn-out fragments of the surface and the retouchings of the edges) show huge similarities to Middle Palaeolithic artefacts from W. Chmielewski’s excavations. The excavation in the Łokietka Cave was most probably located in the cave’s Main Corridor, but determining the precise location is not possible. The trench was most probably never finished as it had been open at the time of the tragic accident in the Ciemna Cave on 4th November 1919. This accident terminated the excavations in the Ciemna Cave, and most probably also in the Łokietka Cave. There is only one artefact originating from S. Krukowski’s excavations in the Łokietka Cave, found 0.75 m below the surface (Fig. 14). This was a bone spoon, with its chronological position, based on analogous finds, for example in Gródek or in Ćmielów, linked to the Neolithic period, more precisely – to the Funnel Beaker culture. S. Krukowski conducted his research in the three abovementioned caves in 1919. In turn, in 1923, as can be deduced from his diaries, he returned to Ojców to do some excavations in yet another cave located in the Sąspowska Valley, i.e. in the Złodziejska Cave. No artefacts have been preserved from these excavations. However, a trench located crosswise to the cave’s corridor is marked on the detailed plan of the cave (Fig. 4), hand-drawn by S. Krukowski, and it is still visible today on the surface of the alluvial deposits in the form of a considerable concavity. According to the information provided by the author in the margins of his drawing, this unfinished trench achieved a depth of 3 m. The results of S. Krukowski’s research broaden our knowledge about the stratigraphy of two sites in the Sąspowska Valley, i.e. the Tunel Stromy the Złodziejska Caves, as well as enabling the addition of new information to the research done during excavations at later sites, such as the Łokietka and the Koziarnia Caves. The present authors hope that this analysis, coinciding with the 100th anniversary of S. Krukowski’s research in the Sąspowska Valley, will allow the artefacts that he discovered there to be circulated more broadly in relevant scientific circles.