Originally published in 1993, this volume describes a complementary selection of tests to those described in the companion volume Basic Mutagenicity Tests (Cambridge University Press, 1990). These supplementary tests were used to assess risks of in vitro mutagenicity in those instances where the basic tests were inconclusive. As such, these tests had an important role in the assessment of the safety of compounds, drugs and chemicals. These supplementary test and guidelines, originally drawn up by the United Kingdom Environmental Mutagen Society (UKEMS) were fully revised in this publication to take full account of different regulatory guidelines and scientific advances. This volume will be of value to anyone with aninterest in regulatory affairs, mutagenicity testing and the registration of chemical products in the UK and Europe.