A method for selecting advertisement in a Set Top Box (STB) of a television network comprises receiving advertisement selection information for one or a plurality of advertisement associations. Each advertisement association associates an advertisement space with an advertisement. The advertisement selection information corresponds for each advertisement association to a value of probability for selecting the advertisement for the advertisement space. A selection of an advertisement for a determined advertisement space is triggered and a random value or a pseudo-random value generated. An advertisement is selected using the random value or the pseudo-random value, by selecting a determined advertisement association that associates an advertisement with the determined advertisement space and for which the corresponding advertisement selection information has a value of probability that relates to the random value or the pseudo-random value. The advertisement associated in the determined advertisement association is used.