The objective of this proficiency study was to provide an initial assessment of laboratory capabilities for the analysis of specific metal trace elements in several tobacco and non-tobacco plant matrices. Laboratories were requested to determine arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), lead (Pb), and selenium (Se) using inductively coupled plasma mass spectrometry (ICP-MS).