The synthesis and antimalarial activity of a series of 2,4-diamino-6-quinazolinesulfonamides (III) is described. Chlorosulfonation of 2,4-quinazolinediamine affords the 6-sulfonyl chloride, which upon treatment with the appropriate amine produces the desired products. Alternatively the sulfonyl chloride could be introduced by diazotization of the corresponding amine followed by treatment with SO2 in the presence of CuCl2. Although substantial antimalarial activity was demonstrated for several members of this class, studies were discontinued in light of the potency of related series.