The changing environment of monoclonal antibody (mAb) development is impacting on the cost of drug development and the use of experimental animals, particularly non-human primates (NHPs). The drive to reduce these costs is huge and involves rethinking and improving nonclinical studies to make them more efficient and more predictive of man. While NHP use might be unavoidable in many cases because of the exquisite specificity and consequent species selectivity of mAbs, our increasing knowledge base can be used to improve drug development and maximise the output of experimental data. Data on GLP regulatory toxicology studies for 58 mAbs were obtained from 10 companies across a wide range of therapeutic indications. These data have been used to investigate current practice and identify study designs that minimise NHP use. Our analysis shows that there is variation in the number of animals used for similar studies. This information has been used to develop practical guidance and make recommendations on the use of science-based rationale to design studies using fewer animals taking into account the current regulatory guidance. There are eight recommendations intended to highlight areas for consideration. They include guidance on the main group size, the inclusion of recovery groups and the number of dose groups used in short and long term chronic toxicology studies.