From a group of pyrrolo[2,3-d]pyrimidine compounds that have been scre
ened against influenza virus, one derivative, 4-(3-piperidinyl benzyla
mino)-2-methyl-7H-pyrrolo[2,3-d]pyrimidine (9), has shown promising ac
tivity against both the A and B strains. The compound had activity com
parable to amantadine, but was inactive when given orally. 4-(Substitu
tedphenyl ethylamino)-2-methyl-7H-pyrrolo[2,3-d]pyrimidines showed no
improved activity.