The two marine algae, Chaetomorpha brychagona and Enteromorpha crinita are found abundantly on the iron ore tailings of Tolo Harbour, Hong Kong, with a rather high level of various metals. Tissue analysis of the algae revealed that the contents of heavy metals (Fe, Mn, Pb and Zn) were higher than in the population collected from the two uncontaminated sites far away from the tailings. It was suggested that the algae were able to adapt to such a harsh environment with a comparatively high level of trace elements and the lack of basic nutrients. However, further studies are needed before any conclusion can be drawn. The delicate situation of the land-locked sea, Tolo Harbour, where the tailings and future heavy industrial site are situated, should not be overlooked. Copyright © 1979 Published by Elsevier Ltd.