Benzo[a]pyrene (BaP), is a ubiquitous environmentalcontaminant present in air, water, andsediment . BaP is readily absorbed by all routes of exposure and can pass directly through the plasma membrane of most cell types. The present study was conducted to examine the effects of BaPon liver tissue structure in orange spotted grouper Epinepheluscoioidesaffected by different concentration of BaP.In the present report, 100 E.coioides were exposed by intraperitoneal injection to 2, 20 and 200 mg/kg of BaPfor 14d under laboratory conditions and the samples were taken from fish liver in days 0, 2, 4, 7 and 14 of experiment for histopathological study. The liver sampleswere fixed in 10%formalin buffer solution. Five-micrometer thick sections were obtained and were stained in hematoxylin/eosin for examination in light microscopy.No pathological alteration was observed in the liver samples of controls fish. The pathological alterations of liver were including of hepatocyte vacuoletion, increase of melanomacrophagecenters, dilation of dissspace, sinusoidal dilation, focal necrosis, hepatocytes hypertrophy, nucleus in a lateral positionand hepatocyte degeneration. The frequency and severity of tissue changes raised with the increase of BaP concentration in all sampling days. The most frequency and severity of histopathological alteration were observed in fish treated by 200 mg/kg BaP in day 7.