A novel series of 4-aminohexahydrocycloocta[4,5]thieno[2,3- d]pyrimidines, hexahydrocycloocta[4,5]thieno[2,3- d]-1,2,3-triazin-4-one and its N-3 substituted derivatives in addition to 3-aryl hexahydrocycloocta[4,5] thieno[2,3- e]-1,4-diazepin-5-ones were synthesised. Also, 2-(N-ethylcarbamothioylamino) hexahydrocycloocta[b] thiophene-3-carbonitrile and 19-imino tetradecahydrocycloocta[4’,5'] thieno[2’,3’:4,5]pyrimido[1,6- a] cycloocta[4,5]thieno [3,2- e]pyrimidine-9-thione were prepared. Almost all the synthesised compounds exhibited anti-tumour activity against human colon carcinoma (HCT 116) cell line in vitro. Five compounds (IC50: 15.92, 22.59, 25.85, 27.40 and 29.70 μM, respectively) exhibited 2.16 to 1.15 fold more potent antitumour activity than imatinib (IC50: 34.40 μM).