Abstract: The present invention provides thienopyrimidine derivatives of the formula (I) ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and each represent hydrogen, halogen, lower alkyl, cycloalkyl or phenyl, R.sub.1 and R.sub.2 taken together may form a ring of an alkylene chain, R.sub.3 represents lower alkyl or a group of the formula ##STR2## (in which R.sub.4 is a lower alkyl, lower alkoxy or halogen, m is 0, 1 or 2, and R.sub.5 is hydrogen or halogen) and Z is oxygen or sulfur, or pharmaceutically acceptable salts thereof, pharmaceutical compositions containing them as an active principle and aldose-reductase inhibitors.