CULTURES of cells from the buffy coat of the blood were described by Carrel and Ebeling in 19221, and since then they have been used by many workers. Several have described the appearance of fibrocytic cells in these cultures2. They have been reported as early as one day after explantation, and Hulliger2, using mainly rabbit buffy coat, found that within one to three weeks cultures of fibrocytic cells were frequently formed in which a high level of mitosis occurred. It would be useful to be able to establish strains of cells from individuals whenever they are required for certain genetic studies, and since the peripheral blood is the easiest tissue to obtain aseptically from volunteers, the possibility that permanent strains might be developed from this source was investigated. Strains were established from four out of five bloods. The technique used is as follows.