A continuous process for the manufacture of a polyamide, the process comprising the steps of: (i) flowing a stream A comprising a molten dicarboxylic acid, or a molten dicarboxylic acid-rich mixture comprising a dicarboxylic acid and a diamine, through a first stage and at least one more reaction stage of a vertical multistage reactor, wherein the first stage is at the top of the reactor; (ii) counter-currently flowing a stream B comprising a diamine as either a vapor or a diamine-rich liquid through at least one of the stages below the first reaction stage of said vertical multistage reactor; (iii) accumulating a liquid phase material P comprising polyamide at and/or below the final stage of said reactor; wherein said reactor is equipped with internal features suitable for effecting contact between counter-currently flowing streams A and B; and wherein said process further comprises the step of agitating said liquid phase material P by injecting a gaseous stream C comprising steam, or at least one inert gas, or a mixture of steam and at least one inert gas into the reactor at or below the final stage of the reactor. The invention further provides a vertical multistage reactor configured to implement said process.