A review of those organic compounds of known structure having analgesic activity has been made. These compounds have been classified according to their parent nuclei and consist of derivatives of benzene, pyrazolone, quinoline, isoquinoline phenanthrene, dibenzofuran and morphine. A comparison of the relative analgesic efficiency of the various compounds has been made, and certain correlations between chemical structure and analgesic action have been pointed out where these have become apparent;A complete list of the derivatives of dibenzofuran which, up to this time, have been submitted from this laboratory and tested for analgesic activity, has been included. The pharmacological results have been discussed in relation to the data given in the literature for similar derivatives in the phenanthrene and morphine series. The available evidence indicates that dibenzofuran derivatives may reasonably be expected to show analgesic activity in a degree comparable to that of similar derivatives of related nuclei;A number of dibenzofuran derivatives, containing nitrogen either in a substituent group or as a member of a fused heterocycle, have been synthesized. Three of these have shown some analgesic activity when tested with white mice;A note regarding the approved nomenclature for imidazole and thiazole derivatives of dibenzofuran has been appended.