A continuous automated extraction system and method for physically extracting at least one liquid phase of a series of liquid microsamples which are taken beforehand in discrete packets, both in space and in time, and are in stored is provided. The method may include an extraction system having a centrifuge provided with a plurality of microholders, at least one of which is filled with the corresponding microsample and includes a filling upper portion that is extended by a separating lower portion of smaller cross section than that of the upper portion. Each filled microholder has a mass which is more than ten times the mass of this microsample, in such a way that it is possible to extract, by centrifugation, at a given instant, only a single microsample contained in a single microholder, or several microsamples contained in some or all of these microholders, progressively as the latter are filled.