Nitrogen factors (the percentage nitrogen on a fat-free basis) for lamb meat were estimated using a total of 81 lamb carcases from the UK. The samples included carcases representative of the EU class ranges for conformation and fatness. The sampling period extended over one year in order to include the three age groups under which lamb meat is marketed. The results obtained were compared with those reported for mutton in Part 1 of this study and a factor of 3.50 for the whole side, on a fat-free basis, for the lean with intermuscular fat was recommended as an overall figure for mutton and lamb. There were significant differences between the factors for some joints and different factors were recommended for use when the type of joint used was known.