Abstract: The reported 2,4-dipiperidino-or 2, 4-dipyrrolidino-6-(substituted) aminoquinazolines were synthesized as potentialantimalarial agents. These compounds were. prepared by reaction of 2,4-dichloro-6-nitroquinazoline with piperidine or pyrrolidine, followed by hydrogenation to form 2,4-dipiperidino-6-aminoquinazoline (Ⅷ₁) or 2,4-dipyrrolidino-6-aminoquinazoline (Ⅷ₂), Ⅷ₁ and Ⅷ₂ condensed respectively with substituted benzaldehydes to afford the corresponding Schiff's bases from which compounds Ⅵ were obtained through hydrogenation and nitrosation. Preliminary screening tests were conducted for both therapeutic and prophylactic activities of these compounds on mice infected either with Plasmodium berghei or P. yoelii. Out of these compounds 16 were shown to possess more or less causal prophylactic activity against P. yoelii. Among them, four compounds (Ⅵ₁₁, Ⅷ₁, Ⅸ₂, Ⅸ₄) were more effective and shown to protect the test mice from being infected at oral doses of 2.5mg/kg in 3 consecutive days.