Twenty-two species of aquatic Diptera have been collected from 16 sites on the Iberian peninsula. Three Dixidae : Dixa nebulosa Meigen, D. puberula Loew, D. submaculata Edwards; three Thaumaleidae: Thaumalea miki Edwards, T. pyrenaica Edwards, T. verralli Edwards ; and sixteen aquatic Empididae (Hemerodromiinae and Clinocerinae): Hemerodromia adulatoria Collin, H. baetica Collin, H. gaditana nov. spec., Wiedemannia mirousei Vaillant, W. fallaciosa (Loew), W. hygrobia (Loew), W. digitata Vaillant, W. tiburica nov. spec, Clinocera barbatula Mik, C. madicola Vaillant, C. tenella Wahlberg, C. nigra (Meigen), C. fontinalis (Haliday), C. stagnalis (Haliday), C. wesmaeli Macquart and Dolichocephala ocellata Costa. Two species are new to science and several others are recorded for the first time in Spain or Andorra, although their occurrence was expected because many records were based on collections from the French Pyrenees.