GnRH receptor antagonists are disclosed which have utility in the treatment of a variety of sex-hormone related conditions in both men and women. The compounds of this invention have the structure: wherein Ar, A, B, Q, R1, R2, R3a, R3b, R6, R7 and m are as defined herein, including stereoisomers, prodrugs and pharmaceutical acceptable salts thereof. Also disclosed are compositions containing a compound of this invention in combination with a pharmaceutically acceptable carrier, as well as methods relating to the use thereof for antagonizing gonadotropin-releasing hormone in a subject in need thereof.