Abstract: 1,2,3,4-Tetrahydrobenzothiopyrano[4,3-c]pyrazol-3-ones and 2,3-dihydro[1]benzothiopyrano[4,3-c]pyrazol-3-ones, of respective structure I and II, ##STR1## wherein n is an integer of value from 0 to 2;R is phenyl; phenyl monosubstituted with chloro, bromo, fluoro, methyl, methoxy, nitro or trifluoromethyl; or phenyl disubstituted with chloro; andX is hydrogen or chloro;are described.These novel compounds are immunoregulators which, through suppression of the immune response in mammals, are useful in inhibiting rejection of organ transplants, as well as in the therapy of auto-immune diseases.