The present invention relates to aqueous polyurethane/urea dispersions wherein the polyurethane/ureas contain 0.5 to 6% by weight, based on the weight of the polyurethane/ureas, of alkoxysilane groups (calculated as Si, MW 28), which have been incorporated by the reaction of isocyanate groups with compounds containing alkoxysilane groups and secondary amino groups other than aspartate groups. The present invention also relates to a process for preparing these aqueous polyurethane/urea dispersions and to coatings prepared from these aqueous polyurethane/urea dispersions.