Eight species of alpheid shrimps are reported for the first time from the coral reef systems off Mexico's northern Yucatan Peninsula (Alacranes, Madagascar and Serpiente Reefs). These species are: Alpheus immaculatus; Alpheus paraformosus; Alpheus punctatus; Parabetaeus hummelincki; Salmoneus depressus; Synalpheus chacei; Synalpheus dominicensis; and Synalpheus elizabethae. The geographical ranges of these species are extended into the southern Gulf of Mexico; most of them are recorded from Mexican territorial waters for the first time. Brief notes on their ecology and taxonomy are provided. Six species are illustrated by colour photographs.