The first contribution in this issue of Animal Welfare is the second of the newly instigated Invited Essays, written at the invitation of the editor and aimed at addressing contemporary welfare problems. It is by Robert Hubrecht, Assistant Director of UFAW and it examines the techniques involved in the genetic modification of animals, and considers the welfare implications and the relevance of the current UK legislation. These essays, which will be an occasional feature of the journal, are refereed by independent experts but very much represent the personal views of the authors. Hopefully some of the opinions expressed will stimulate readers to respond with constructive critical comments, which could be published in the journal's Letters section. The original author will of course have the right to reply.