Correlations of malignancy grade, immunologic phenotype and angiogenic capacity were studied in B-cell non-Hodgkin's lymphomas grafted onto chorioallantoic membranes of chicken embryos. The angiogenic response elicited by the tumors was significantly greater than the response to normal lymph nodes, but it did not correlate with either the malignancy grade or the immunologic phenotype of the tumors. The elevated angiogenic capacity of neoplastic tissues is confirmed. The results also suggest that the extensive vasoproliferative response required by a rapidly growing tumor is not only controlled by the neoplastic cell population but, probably, by the host-response as well.