Taking part in a proficiency test (PT) gives a laboratory an independent assessment of their performance. These results can be used for many purposes, as an interlaboratory comparison, for long-term trend analysis, continuous assessment for quality systems/regulatory purposes, for customer confidence and for regulatory compliance. Details of the proficiency test samples used will be outlined to provide a basis for discussion of tobacco proficiency test matrix variability, challenge and frequency of schedule. These results will lead to whether PT tobacco samples should be characterised / certified further so that they may be used as reference materials post proficiency test.