The object of this invention is aimed at making easier for people with reduced mobility to go upstairs or downstairs. In order to reduce the height of the steps of a stairs previously manufactured, an integral assembly is inserted in one of its laterals working as auxiliary steps, adjustable in height, with less width than the width of the original steps over which the ensemble is placed, following the pattern described in the upper figure.The user of such stairs previously manufactured can use the present invention in an auxiliary way, putting one foot or two feet over the ensemble before moving towards a new step. This way the effort necessary to climb the step of the stairs on which it is placed is reduced, as well as the height up to which the feet have to go, being especially useful for aged people or people with articular problems.The improvements on the auxiliary stairs for people with reduced mobility mainly focus on the folding mechanism of the stairs. To this purpose, the possibility of folding the steps has been taken into account, in order to get a better exploitation of the space.