The invention provides agents useful for treating pain. An exemplary agent comprises or consists of the a portion of a retroviral Tat protein. One such agent is the peptide Tat-NR2B9c. This peptide has previously been described as an agent for inhibiting damaging effects of stroke and similar conditions via inhibition of PSD95 interactions with NMDA receptors and/or NOS. The present application provides data showing that the Tat-NR2B9c peptides is effective in alleviation of pain. The alleviation of pain can be obtained at a dose of the peptide below the dose required to inhibit PSD-95 interactions with NMDAR or NOS.