Abstract: Seventeen 2,4-diamino-6-substituted amino sulfonyl quinazoline derivatives were tested for antimalarial activity on mice infected with several strains of Plasmodium berghei. In preliminary experiments, compounds I₄, I₅,I₁₀, I₁₁ and I₁₂ showed marked antimalarial activity. The SDs0 of these compounds against infections with N strain were 0.43～2.4 mg/kg×4d, PO; with NK₆₅ strain 7.2～100 mg/kg×4d, PO; with chloroquine resistant RC line 0.19～0.42 mg/kg×4d, PO; and with sulfonamide resistant ORA Iine 11～76 mg/kg×4d, PO.These results indicate that there is no cross resistance between these compounds and chloroquine. The RC line was shown to be more sensitive than the N strain. Some degree of cross resistance exists between these compounds and sulfonamides.