The present invention pertains to a water-redispersible polymer powder composition based on at least one synthetic polymer and at least one natural latex. Preferably, the polymer powder contains up to about 90 wt. % of at least one water-insoluble, synthetic polymer, up to about 90 wt. % of least one natural latex, about 0 to 50 wt. % of at least one protective colloid, about 2 to 50 wt. % of at least one filler and/or anti-caking agent, as well as optionally further additives. In addition, the invention pertains to a process for the preparation of the polymer powder composition, the use thereof as an additive in building material compositions, as well as building material compositions containing the polymer powder composition.