Background: The families Xanthdiae and Pilumnidae are two common families of the brachyuran crabs in the Persian Gulf. These families are represented with 25 and 23 species, respectively, in the Gulf. Methods: Brachyuran crabs from Abu-Musa Island, Iran, Persian Gulf have been collected and examined for a biodiversity project conducted during 2014 and 2015. The material was mostly collected from the intertidal and shallow subtidal using hand and snorkeling. Results: In total, 16 Xanthidae species were identified, of which four are new records for the Persian Gulf and include Atergatis integerrimus (Lamarck, 1801), Zosimus aenus (Linnaeus, 1758), Zozymodes cavipes (Dana, 1852), Macromedaeus crassimanus (A. Milne-Edwards, 1867). One further new record for the Persian Gulf is the pilumnid Cryptopilumnus pereiodontus (Davie and Ghani, 1993).