A series of N‐substituted 8‐aminoxanthines (=8‐amino‐3,7(or 3,9)‐dihydro‐1H‐purine‐2,6‐diones) 8–16 and 34–37 were synthesized from the corresponding 8‐nitroxanthines 1–7, 30–33, and 8‐(phenylazo)xanthines 17 and 18 by catalytic reduction. Another approach was derived from 6‐amino‐5‐(cyanoamino)uracils (=N‐(6‐amino‐1,2,3,4‐tetrahydro‐2,4‐dioxopyrimidin‐5‐yl)cyanamides) 23, 24, and 27 by base‐catalyzed