The soil and vegetation contamination by the iron-ore tailings, Ma On Shan in Hong Kong was investigated. The semi-bare ground was sparsely covered with herbaceous vegetation dominated by Neyraudia reynaudiana and Urena lobata. The soils were alkaline, low in organic carbon and basic nutrients, containing large amounts of fine particles together with high concentrations of some metals: Mg, Ca, Na, Fe, Mn and Cu. The uptakes of Mg, Fe, Mn and Cu by N. reynaudiana were also high compared with those growing on the control site. The harmful effect of the high metal contents in the tailings was further demonstrated by the cultivation of seedlings of Brassica parachinensis in the soil-water extracts. It was concluded that the factors governing the establishment and colonisation of the plants on the iron-ore tailings might be the high metal contents and other adverse edaphic factors. Copyright © 1977 Published by Elsevier Ltd.