The quality of fish (anchovy, horse mackerel, whiting, sea bass and sea bream), selling in Istanbul market, were studied. Samples were obtained from the retail fish markets located in three main regions (Region I= Kadikoy, Region II=Besiktas and Region III= Kumkapi) of Is-tanbul. According to the results of sensory, chemical and microbiological analysis; quality of the samples was lower (P0.05) in summer then the other seasons due to the high ambient temperatures (32 ±2ºC), and samples obtained from Region III (Kumkapi) was generally better (P0.05) than the others. Istanbul wholesale fish market, the seafood supplier of the retailers, is also located in Kumkapi. Therefore transport of fish from whoesale market to the retailers in Region III is easy and fast. However, wolesale fish market is far from the local markets in Region I and II. Thus, it was concluded that unsuitable transport conditions of fish from whole sale market to the retailers are the main reasons of poor quality. Vehicles must be equipped with a cooling system, and retailers should properly refrigerate seafood especially in summer season. It is mandatory to apply Turkish legislation of 2002, which is on the regulation of sea-food market conditions and harmonious with EC (European Commission) criteria.