This study is a revision of the Iberian Merodon Meigen, 1803 species, including an illustrated key, a discussion of taxonomic characters and a morphological diagnosis for all included species. Descriptions are provided for nine new species: M. antonioi sp. n., M. arundanus sp. n., M. cabanerensis sp. n., M. crypticus sp. n., M. hurkmansi sp. n., M. legionensis sp. n., M. longispinus sp. n., M. luteihumerus sp. n. and M. quercetorum sp. n. The taxon M. escorialensis Strobl, 1909 is redescribed and lectotype is designated. Lectotypes are designated for four taxa: M. albifrons Meigen, 1822; M. spinipes obscuritarsis Strobl in Czerny & Strobl, 1909; M. spicatus Becker, 1907; and M. spinipes grossus Gil Collado, 1930. Three varieties are redefined and considered as valid species: M. obscuritarsis Strobl in Czerny & Strobl, 1909 (as var. of spinipes); M. grossus Gil Collado, 1930 (as var. of spinipes); M. unicolor Strobl in Czerny & Strobl, 1909 (as var. of aeneus). The following new synonymies are proposed: M. affinis Gil Collado, 1930 syn.n. (= junior synonym of M. longicornis Sack, 1913); M. lusitanicus Hurkmans, 1993 syn.n. (= junior synonym of M. serrulatus Wiedemann in Meigen, 1822); M. andalusiacus Paramonov, 1929 syn.n., M. bolivari Gil Collado, 1930 syn.n., M. hispanicus Sack, 1931 syn.n. (= all three are junior synonyms of M. unguicornis Strobl in Czerny & Strobl, 1909); M. spicatus Becker, 1907 syn.n. (= junior synonym of M. chalybeus Wiedemann in Meigen, 1822); M. fuerteventurensis Barkemeyer, 2002 syn. n. (= junior synonym of M. obscuritarsis Strobl, 1909); and M. spinipes grossus (Gil Collado, 1930) syn.n. (= junior synonym of M. albifrons Meigen, 1822). Status of M. serrulatus Wiedemann in Meigen, 1822 is revised. Four species: M. longicornis Sack, 1913, M. pumilus Macquart, 1849, M. ottomanus Hurkmans, 1993 and M. segetum (Fabricius, 1794) are new for the Iberian Peninsula. Male genitalia are illustrated for all the species and a key of the 34 Iberian species (+ M. hurkmansi sp. n.) for males and females (except for the unknown female of M. longispinus sp. n.) is appended. Distribution and biological data for the Iberian species are also included. A brief zoogeographic discussion is also presented. The level of endemism of genus Merodon on the Iberian Peninsula is extremely high (almost 50%).