Bifunctional derivatives of benzothieno[2,3-d]pyrimidine have been synthesized and tested for antituberculous activity. 7-Bromo-8-hydroxy-2,3-trimethylene-4-oxy-3,4-dihydrobenzothieno[2,3-d]pyrimidine and 2-amino-3-ethoxycarbonyl-6-bromo-7-hydroxybenzo(b)thiophene were found to have tuberculostatic activity, whereas 7-bromo-8-hydroxy-2,3-pentamethylene-4-oxy-3,4-dihydrobenzothieno[2,3-d]pyrimidine, 7-bromo-8-hydroxy-2,3-(tetramethylene-2-oxa)-4-oxy-3,4-dihydrobenzothieno[2,3-d]-pyrimidine, 7-bromo-8-methoxy-4-oxy-3,4 - dihydrobenzothieno-[2,3-d]pyrimidine, and 7-bromo-8-benzyloxy-4-oxy-3,4-dihydrobenzothieno[2,3-d]pyrimidine were devoid of antituberculous activity.