The relationship between the coagulating properties of slurry suspensions, type of packing liquids, and final performance of slurry-packed microcolumns for liquid chromatography (LC) was investigated. The colloidal stability of stationary-phase suspensions was examined by means of sedimentation and 6-potential experiments. Expressions for the theoretical sedimentation rate of noncoagulated particle suspensions were derived for spherical particles with completely and incompletely filled pores and for imegularly shaped particles with incompletely filled pores. The performance ofthe slurry-packed microcolumns was predominantly determined by the selection of the packing liquid. It is shown that the packing liquid preferably has to be coagulating to obtain efficient and stable packed capillary- LC columns. The selection of the slurry liquid on the column performance was of minor importance.