Abstract: Peptides having the formulaN-Acetyl-N-methylglycyl-L-histidyl-L-tryptophyl-L-seryl-L-tyrosyl-Y-L-leucy l-L-arginyl-L-prolyl-Zwherein Y is a D-.alpha.-alkylglycine residue of the formula ##STR1## in which n is an integer of 0 through 3 inclusive and Z is ethylamino group or an ethylamino group which is substituted with 1 to 3 fluorine atoms at the 2-position and pharmaceutically acceptable salts thereof. They show luteinizing hormone-releasing hormone like activities and are prepared by reactingL-histidyl-L-tryptophyl-L-seryl(or L-seryl having a protected hydroxyl group)-L-tyrosyl(or L-tyrosyl having a protected hydroxyl group)-Y-L-leucyl-L-arginyl(or L-arginyl having a protected guanidyl group)-L-prolyl-Zwherein Y and Z are as defined above witha reactive derivative of N-Acetyl-N-methylglycineAnd, if a protective group is attached, then removing the protective group, and, if necessary, converting further the resultant into an acid addition salt thereof in the usual manner.