In Hong Kong, the toxicity of oil spill dispersants was assessed in a preliminary screening test, based upon TD50 values in samples of ten fish. Later, an improved test was introduced, based upon new procedures developed in the United Kingdom and modified to suit conditions in Hong Kong. Products approved elsewhere were usually, but not always, approved in Hong Kong. Further work is needed to relate the test results to oil-spill damage in local waters. Copyright © 1981 Published by Elsevier Ltd.