This invention relates to a one-step process for preparing polyurea elastomers comprising reaction at an isocyanate index of from 90 to 200 of(a) one or more aliphatic and/or cycloaliphatic diisocyanates;(b) 25 to 70 equivalent percent, relative to the total of components (b) and (c), of one or more liquid amine-terminated polymers containing at least two aromatically bound isocyanate-reactive primary or secondary amino groups and/or aliphatically bound isocyanate-reactive secondary amino groups and having a molecular weight of from 400 to 6000; and(c) 75 to 30 equivalent percent, relative to the total of components (b) and (c), of one or more aromatic diamine chain extenders having a molecular weight of from 108 to 399, optionally in admixture with one or more crosslinkers.