In previous work, two anatomically distinct‐liver sinusoid endothelial cells (LEC): LEC‐1 and LEC‐2, have been described. We also reported that extramedullary hepatic hematopoiesis occurs only in close contact with LEC‐1, suggesting that these cells may provide the microenvironment necessary for the maintenance and growth of hematopoietic cells. In the present work, we studied the capacity of LEC‐1 and LEC‐2 to maintain in vitro hematopoiesis. LEC‐1 and LEC‐2 were isolated and cloned from livers of adult mice. Bone marrow cells (BM) enriched with primitive hematopoietic progenitors were isolated from day‐2, post‐5‐FU‐treated mice (5‐FUBMC). LEC‐1 supported the maintenance and differentiation of hematopoietic progenitors for more than 6 weeks in vitro. In contrast, LEC‐2 cells poorly supported the proliferation of hematopoietic cells for only two weeks of the co‐ culture. LEC‐1 and 5‐FUBMC cocultures showed cobblestone‐area formation and the presence of hematopoietic progenitors that are able to form colonies (CFC) in the adhering fraction after six weeks of coculture. LEC‐1 co‐cultures treated with a cocktail of cytokines (stem cell factor, interleukin [IL]1α, IL‐3, and Epo) showed that megakaryocyte (CFU‐Mk) and erythrocyte progenitors (BFU‐e) were present during the entire period of the culture. Granulocyte‐macrophage progenitors (CFU‐GM) were present only during the first three weeks of the culture. These results suggest that LEC‐1, but not LEC‐2, provide an appropriate hematopoietic microenvironment for supporting the proliferation and differentiation of primitive hematopoietic cells. This could explain the anatomical restriction of hematopoietic cells for growing in LEC‐1 domains during liver extramedullary hematopoiesis.