One hundred and eight yellow-fin seabream (Acanthopagrus latus) with approximate weight 110±20g, adapted to salinity 20 ppt for 14 days, then challenged suddenly to salinity 5 ppt, 12 ppt, 34 ppt and kept in these salinities for 7 days. Gill samples were taken at 0, 24, 48 hours and 7 day after transfer. At time 0 structure of gill was normal and no changes were recorded in distribution of gill constitutes. Area of chloride cell increased in all groups after salinity challenge, but after one week at 12 and 34 ppt salinity, area of chloride cell decreased. Gill microscopic structure was normal and no changes was recorded in arrangement of the gill components. Size of chloride cell showed increase in fish kept in changed salinities, but decreased in 12 and 34 ppt groups after one week. Some changes including hypertrophy and hyperplasia of gill epithelium, lifting the gill epithelium, hypertrophy of chloride cells, changes in chloride cells area, adhesion Lamella and had an aneurysm were recorded in all groups. Our findings showed that some structural changes was seen in gills of A. latus to be compatible with different salinities