Plankton samples were taken at fortnightly intervals from January 1986 to June 1987 at six stations 20-50 km north of Jeddah, Saudia Arabia: three in a mangrove area ( Zahban village) , two outside the mangrove area ( Thuwal village) and one off Obhor Creek. Larvae of decapod Crustacea ( excluding the Brachyura ) were identified as far as possible and descriptions are given of the anomuran larvae encountered . Studies were made on seasonal variations in the numbers of larvae and on differences in occurrence and abundance between the stations. Eighty nine species of A/pileus larvae were distinguished , largely using differences in chromatophore pattern. Only two species of adult A/pfJeus are recorded from the central Red Sea. Thirty seven unnamed species of Anomura were distinguished on morphological characters and these are described and figured. The anomuran larvae belong to the fo1lowing families : Upogebi1dae ( 4 species ) , Callianassidae ( 7 species) , Laomedi1dae ( 2 species) , Galatheidae (7 species) , Porcellanidae ( 6 species) , Paguridae ( 4 species) , Diogenidae ( 7 species ) , and the Dlogenidae are made up of the fo1lowing genera: Oiogenes ( 2 species), Ca/cinus ( 2 species) , Dardanus ( 2 species ) , Clioanari(Js ( 1 species ) . Ten genera of Macrura, belonging to seven families, are also listed.Descriptions are g1ven of the complete larval development of Coenobita sceevole ( Forskal ) ( Coenob1tidae ) and Dardanus ttoctor ( Forskal ) ( Diogenidae ) I based on laboratory rearing. Comparisons are made with the larvae of related species . The presence of a central telson sptne in zoea III and all subsequent zoeal stages 1s a feature of all known coenootttd larvae, although 1t does not occur 1nother larvae of the Anomura ( sensu stricto) ( i. e. excluding the tnatasstntoae ) . The concentration of decapod larvae over the 18 months at the d1fferent stations was fairly strnttar I averaging about 1190/1000 m3 . The most common anomuran larvae were those of the Dtoqentdae , w1th Diogenes avarus Heller the most common 1n the mangrove area and the unnamed spec1es Ca/ein(Js A the most common off Obhor Creek. Larvae of A/pneus spp. and Harpil/us spp. made up a large percentage of the decapod larvae I especially at the stations outside the mangrove area and off Obhor Creek . Larvae of Galatheldae I Paguridae and Callianassidae were conspicuously more abundant 1n the night samples than 1nthe day samples. During the e1ghteen months of sampling at the six stations I decapod larvae tended to be more common 1n summer, particularly in June. More sampl1ng would be reoutrec to establ1sh whether th1s 1s a regular annual feature.