LYMPHOCYTE-induced angiogenesis (LIA) has been introduced by Sidky and Auerbach¹ as a quantitative and sensitive assay for measuring cell-mediated immunity in vivo. In this assay immuno-competent lymphocytes are injected intradermally into allogeneic or semiallogeneic mice. A local graft versus host (GVH) reaction is therefore induced, resulting in new blood vessel formation. As early as the second day post-injection, this effect could be observed in a doseâ response fashion dependent on the number of cells injected. The relationship of lymphocyte-induced angiogenesis to tumour-induced angiogenesis mediated by tumourâ angiogenesis factor (TAF)² remains theoretical. Folkman and others have demonstrated inhibition of TAF-induced angiogenesis by cartilage fragments³ or extracts⁴. In this study we show that isolated chondrocytes can inhibit the angiogenesis induced by lymphocytes in vivo. Their ability to do so depends on the ratio of chondrocytes to lymphocytes used.