Many of the improvements in the welfare of laboratory animals over the last 10 or so years have come about through the application of the principles of the 3 Rs: replacement, reduction and refinement, originally put forward in 1959 by Russell and Burch. More recently the term alternatives is being used to mean, in a precise sense, replacement and less precisely all three of the Rs. Application of these principles has resulted in a decrease in the number of animals used and a lessening of the amount of suffering. These developments have been welcomed by the scientific community and the legislators as well as by animal welfarists.