Abstract: In view of the facts that moderately electron withdrawing carrier might cause the triazenes increase their antitumour activity and decrease their toxicity, sixteen 8-triazenopurines were prepared. 7-H-8-triazenopurines were synthesised by coupling the corresponding 8-diazopurines directly with appropriate secondary amines under carefully controlled conditions, while 7-alkyl-8-triazenotheophyllines were obtained by coupling 8-diazotheophylline with secondary amines to 8-triazenotheophyllines and subsequent alkylation under suitable conditions.All sixteen compounds have been subjected to experimental antitumour tests. Preliminary results revealed that compounds 2a, 3a, 4a and 5 showed marked inhibitory action against L₆₁₅ in mice with an ILS of 300～400%, among them compound 4 a exhibited highest -activity but less toxicity. Further study is in progress.