Pyrazole derivatives of the formula: ##STR1## and pharmaceutically acceptable nontoxic salts thereof wherein R is hydrogen, trifluoromethyl or alkyl;R.sup.1 is hydrogen or alkyl;R.sup.2 is alkyl;R.sup.3 is a substituted aryl moiety orR.sup.3 is naphthyl or pyridyl; andR.sup.4 is R.sup.5 CO wherein R.sup.5 is alkyl unsubstituted or substituted by 1, 2 or 3 halogen moieties, by alkoxy, or by mono- or dialkylamino; lower alkoxy; dialkylamino; thiophene; phenyl unsubstituted or substituted by 1 or 2 alkyl, trifluoromethyl, alkoxy, nitro or halogen moieties; or a 5- to 7-membered heterocycle unsubstituted or substituted by 1 or 2 halogen, alkyl or nitro moieties; orR.sup.4 is Z-SO.sub.2 wherein Z is alkyl, phenyl or phenyl substituted by 1 or 2 alkyl, halogen, nitro, trifluoromethyl or trifluoromethylsulphonyl moieties; or dichloroquinoxalinyl. The pyrazole derivatives and their salts are useful as diuretics, saluretics and antihypertensives.