A washing-agent dispenser for machines for washing, in particular dishwashers, comprises: • - a dispenser body (11) with at least one receptacle (12, 12a) for containing a washing agent; • - at least one hatch (20) having a hatch body (21) mounted in a guided way relative to the dispenser body (11) for being slidable between a position of closing and a position of opening of the at least one receptacle (12, 12a), the hatch body (21) having two longitudinal sides (21b, 21c) generally parallel to one another and with respect to a direction of displacement of the hatch body (21) between the position of opening and the position of closing; and • -a guide arrangement (25-27, 30a-30b, 31a-31b) between the dispenser body (11) and the hatch body (21), for guiding displacement of the hatch body (21) between the position of opening and the position of closing. The guide arrangement (25-27, 30a-30b, 31a-31b) comprises at least one movable guide element (25), in a position corresponding to a respective longitudinal
