To understand the distribution characteristics of nonylphenolics and sterols, samples such as in creek water, sea surface water, waste water treatment plant (WWTP) effluent water, sediment and mussel were collected and analyzed. The principal analytes are nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), coprostanol (5beta) and cholestanol (5alpha). All these target pollutants showed 100% detection frequency in all of the samples analyzed. Total concentration of nonylphenolic compounds ranged from 334 to 3628ngl(-1) (average: 1331ngl(-1)) in creek water, from 15 to 36400ngl(-1) (average: 1013ngl(-1)) in sea surface water, from 131 to 2811ngg(-1) dry weight (average: 581ngg(-1) dry weight) in sediment and from 50.5 to 289ngg(-1) dry weight (average: 139ngg(-1) dry weight) in mussel. For water samples, levels of nonylphenolics determined in summer season were higher than those in spring season. Among them, nonylphenol and NP1EO was dominant in creek water and seawater, respectively. The highest concentration was recorded in sediment near a WWTP effluent outlet. And high levels of nonylphenolics and sterols were found in about 3km area surrounding WWTP effluent outlet. Coefficient of linear regression (R(2)) for NP in mussel and in sediment was 0.90. Similarly good correlation (R(2)=0.98) was obtained between concentration in water and in mussel indicating that a steady state has been reached in this bay. The calculated bio concentration factor (BCF=2990) for NP in Masan Bay agrees well with reported values in the literature.