Novel compounds which selectively bind to the .delta.-opioid receptor have been designed. These compounds have greater selectivity, improved water (blood) solubility, and enhanced therapeutic value as analgesics. Because agonists with selectivity for the .delta.-opioid receptor have shown promise in providing enhanced analgesis without the addictive properties, the compounds of the present invention are better than morphine, naltrindole (NTI), spiroindanyloxymorphone (SIOM), and other known .mu.-opioid receptor selectors as analgesics.