When heterotopically transplanted under the renal capsule, the strains of stromal fibroblasts from spleen cultures formed the lymphoid organs, which had no specialized structures, such as red and white pulp and consisted of the accumulations like lymphoid follicles. The purpose of the given work was the study of ability of spleen stromal fibroblast strains, when heterotopically transplanted into the organism, to transfer the specific lymphoid microenvironment. The heterotopic transplantation of spleen fragments and stromal cells, grown in vitro, was made in autologous variant. The spleen fragments were put under a renal capsule. The strains of stromal fibroblasts of 5-7th passages were put into porous frames under a renal capsule of normal or immunized rabbits. The immune response to sheep red blood cells was studied in spleen of normal and hyperimmune rabbits, in regenerating spleens, in heterotopic grafts of spleen and in lymphoid organs, formed by strains of spleen stromal fibroblasts, grown in cultures. The immune response was determined on the 7-8th day after immunization by counting the amount of plaque forming cells (PFC) by Jerne method. In lymphoid organs, formed at the place of transplantation of spleen stromal fibroblasts strains of rabbits, the number of PFC was almost 3 times lower, than in heterotopic transplants of spleen, and 6 times lower, than in normal and regenerating spleens, but hundreds times exceeding the number of spontaneous PFC which could be only found, when 10(7)-10(8) spleen cells of normal non-immunized animals were tested. The concentration of PFC in lymphoid organs, formed at the place of the graft of stromal fibroblasts, was 3 times lower in regenerating spleens of hyperimmunised animals and 5 times higher, than in transplants of stromal fibroblasts of normal spleen. The obtained results give an evidence, that the transplantation of spleen stromal fibroblasts provides the transfer of specific lymphoid microenvironment.