The present invention relates to a method for selecting a virtual slot to start up an instance of an application in a distributed system comprising a plurality of physical machines distributed on a network, each physical machine housing at least one virtual machine, and each virtual machine comprising at least one virtual slot for running an application instance in said virtual machine.The method according to the invention comprises selecting an application slot to start up an instance of an application including the following steps: determining a set of free application slots, i.e., those not occupied by an application instance in use, computing a score for each free application slot, the score computation depending on at least one constraint, selecting the application slot to start up the considered application instance, said selected application slot being that having the best score.