Globotriaosylceramide (Gb3) and globotetraosylceramide (Gb4) are the proposed functional receptors for Shiga toxin (Stx). To elucidate the effect of Gb3 content on Stx-induced cytotoxicity in HeLa cells, we cloned HeLa cells and determined the correlation between glycolipids content and Stx-induced cytotoxicity. The 29 HeLa cell clone (HLCC) lines used showed a wide range of sensitivity to Stx, compared to Gb3-rich cells which were more sensitive, showing as little as 20% viability to 100 pg/ml Stx. In contrast, Gb3-deficient cells proved resistant as they were more than 80% viable to 100 ng/ml Stx. Gb3 content in the HLCC lines corresponded with Stxs-induced cytotoxicity as well as Gb3 synthase expression, but no correlation with Gb4 content was noted. These data show that Gb3 content, which is regulated by the expression of Gb3 synthase, determines the sensitivity of HeLa cells toward Stx.