We have compared the EBV‐receptor concentration of two originally EBV‐negattve human B‐cell lymphoma lines, after in vitro conversion with the transforming B95‐8 or the cytopathic P3HR‐1 EB‐viral substrain, respectively, into permanent EBV‐carrying sublines. Receptors were measured by the quantitative EBV‐absorption bioassay of Sairenji and Hinuma (1973). EBV receptor concentration of all P3HR‐1 virus‐converted sublines was significantly reduced, in comparison with the B95‐8 virus‐converted sublines. This suggests that cells with a low receptor concentration are more likely to survive the initial infection with the P3HR‐1 viral harvest. The results further confirm the biological differences between the two EBV substrains. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company