Peptides which exhibit high selectivity for the kappa opioid receptor (KOR) and long duration of peripheral action without significant entry into the brain are created which are sequences of four D-isomer amino acid residues having a C-terminus which is a mono or di-substituted amide. Representative compounds, which have an affinity for the KOR at least 1,000 times their affinity for the mu opioid receptor and an ED.sub.50 of not greater than about 0.5 mg/kg, includeH-D-Phe-D-Phe-D-Nle-D-Arg-NHEt,H-D-Phe-D-Phe-D-Nle-D-Arg-morpholinyl,H-D-Phe-D-Phe-D-Nle-D-Arg-NH-4-picolyl,H-D-Phe-D-Phe-D-Nle-D-Arg-NHPr,H-D-Phe-D-Phe-D-Nle-D-Arg-thiomorpholinyl,H-D-Phe-D-Phe-D-Nle-D-Arg-NEt.sub.2,H-D-Phe-D-Phe-D-Nle-D-Arg-NHMe,H-D-Phe-D-Phe-D-Leu-D-Orn-morpholinyl,H-D-Phe-D-Phe-D-Nle-D-Arg-NHhEt,H-D-Phe-D-Phe-D-Nle-D-Arg-NH-cyclopropyl,H-D-Ala(2Thi)-D-4Cpa-D-Leu-D-Arg-morpholinyl,H-D-Phe-D-Phe-D-Nle-D-Arg-piperidinyl,H-D-Phe-D-Phe-D-Leu-D-Orn-NHEt,H-D-Phe-D-Phe-D-Leu-D-Lys-morpholinyl,andH-D-Phe-D-Phe-D-Nle-D-Arg-piperazinyl.