With the objective of seeking substances which have antitumor or antiviral properties, in the present work we have studied the aminomethylation reaction [i] of some uracil (I) de- rivatives, specifically 6-methyl-I (II), 6-methyl-2-thio-I (III), 5-methyl-I (thymine, IV), 5-hydroxymethyl-6-methyl-I (V), and