Abstract: Process for the preparation of polyamide-12 powder by anionic polymerization of lauryllactam in solution in a solvent of the said lactam, the polyamide-12 powder being insoluble in this solvent, the said polymerization being carried out: in the presence of a catalyst and of an activator; in the presence of a finely divided organic or inorganic filler, the proportion of this filler being less than or equal to 1.5 g per 1000 g of lauryllactam; adn in the presence of an amide of formula R1-NH-CO-R2 in which R1 can be replaced by an R3-CO-NH- or R3-0-radical and in which R1, R2 and R3 denote an aryl, alkyl or cycloalkyl radical, the proportion of this compound being between 0.001 mol and 0.030 mol per 1000 g of lauryllactam.