Novel therapeutically active derivatives of benzamide, having the general formula ##STR1## in which R.sub.1 and R.sub.2, independently of each other, are hydrogen or a lower alkyl group, R.sub.3 is a phenyl or lower alkyl or lower alkenyl group, R.sub.4 is a halogen or a trifluoromethyl or nitro-group, R.sub.5 is a sulphamoyl or carboxyl or carboxy-alkyl group, and the potassium salts of these derivatives. These compounds are diuretics and hypotensors (blood pressure depressants) and they lower the angiotensin and renin functions, with prolonged action.