The levels and trends of organochlorine contaminants were determined along the Spanish Mediterranean coast from 2000 to 2013 using mussel, Mytilus galloprovincialis, as bioindicator species. The highest levels of PCBs and DDTs were found at industrial and urban locations, and at areas under the influence of the mouth of major rivers. Dieldrin and t-NNC were commonly detected, while HCHs, aldrin, isodrin, endrin and HCB were at levels not detectable at many areas. Significant declines on the levels of DDTs were observed at most of the areas studied. Conversely, no trends or weak downtrends for PCBs were observed in the areas more polluted by local sources, and in most areas less polluted, where PCBs inputs may be primarily from the atmosphere. Upward trends for PCBs were found in some areas from the Alborán Sea, probably related to the inputs of PCBs through the Strait of Gibraltar. Background concentrations for PCBs and p,p'-DDE have been calculated for this Mediterranean region.