The invention relates to phosphorus-containing flame retardant agglomerates comprising a) from 99.99 to 80% by weight of aggregates and/or primary particles composed of a phosphinic salt of the formula (I) and/or composed of a diphosphinic salt of the formula (II), and/or composed of polymers of these, where R1,R2 are identical or different and are C1-C6-alkyl, linear or branched, and/or aryl; R3 is C1-C10-alkylene, linear or branched, C6-C10-arylene, -alkylarylene or -arylalkylene; M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K and/or a protonated nitrogen base; m is from 1 to 4; n is from 1 to 4; x is from 1 to 4 and b) from 0.01 to 20% by weight of auxiliaries. The invention likewise relates to a process for the production of these phosphorus-containing flame retardant agglomerates, and also to polymeric compositions and moldings which comprise these phosphorus-containing flame retardant agglomerates.