The rat is often used when the sympathetic nervous system contribution to various physiological and pathological processes is studied. These experiments require a detailed knowledge of the lumbar sympathetic chain anatomy since the macroscopic anatomy of the L2 and L3 levels of the sympathetic chain, which innervate a major portion of the hindleg, is highly variable. We have performed a detailed study of the anatomy of the lumbar sympathetic chain in 245 Sprague-Dawley rats. Through anatomical characterization of the L2 and L3 sympathetic ganglia white and gray ramus communicants, our study provides an anatomical guide for studies of the function of the lumbar sympathetic chain in the rat.