Purpose <p>The aim of this study was to assess the quality of harbour sediments for potential agricultural use.</p> Methods <p>The study evaluated the granulometric composition, pH, salinity, cationic sorption capacity, total organic carbon, macronutrients, trace elements, PAHs, radionuclides and ecotoxicity of seven sediment samples collected from Sydney Harbour (Australia).</p> Results <p>The sediments had relatively low organic carbon content and Na⁺ ions were dominant in the sorption complex due to significant salinisation of the bottom sediments. The sediments presented a higher environmental risk due to metal/metalloid content than PAHs and radionuclides. A major problem for agricultural use of bottom sediments was contamination with metals (Zn, Pb, Cu, Hg, Ni) and salinity. Levels of the above metals were found to be above acceptable limits for bottom sediment/soil. Bottom sediment salinity was an important factor influencing ecotoxicity. There was a significant positive correlation between salinity and root growth inhibition of <i>Sinapis alba</i> and <i>Sorghum saccharatum</i>.</p> Conclusion <p>Immobilisation/extraction of metals, removal of salinity or enrichment of sediments with organic matter may improve the potential of these harbour sediments for land application.</p>