INTRODUCTION AND OBJECTIVE: Cancer patients have a 4- to 7- fold increased risk of venous thromboembolism (VTE). Cancer-associated thrombosis is a major cause of morbidity and one of the main causes of death in these patients. Currently, mouse models are used to study the mechanisms involved in this pathology and to allow preclinical testing. However, mouse models cannot be used to properly mimic the human pathology, since mice do not develop thrombosis spontaneously. The biological mechanisms involved in cancer-associated thrombosis are still unknown. Our main objective was to develop a humanized organ-on-a-chip model to study cancer-associated thrombosis. MATERIAL AND METHODS: The OrganoPlate Graft (Mimetas BV) was used as a platform to mimic a cancer-associated thrombosis environment. Human umbilical vein endothelial cells (HUVECs) were isolated, expanded and seeded in the perfusion channels from the OrganoPlate Graft. In parallel, spheroids of HT-29 human colorectal cancer cell line were generated using 10,000 cells/well which were seeded in non-adherent round bottom 96-wells plates. After 3-4 days of HUVEC and spheroid seeding, pro-angiogenic growth factors or colorectal cancer spheroids were added to the graft chamber. After another 3 days of co-culture, the model was assessed for cell morphology, barrier permeability, and thrombin formation. RESULTS AND CONCLUSION: Our data showed that the addition of pro-angiogenic growth factors or colorectal cancer spheroids increased the permeability of the endothelial barrier. Pre-incubation of endothelial cells with TNF-α induced thrombin generation after the addition of citrated human plasma and calcium. Moreover, there was more thrombin generation when colorectal cancer spheroid or pro-angiogenic growth factors were added. Our data showed that the cancer-associated thrombosis model is a promising model to study this pathology in vitro incorporating a 3D environment in a microfluidic system.