One-hundred-ten samples of onion (Allium cepa Hysam) from 11 Danish sites (10 onions from each site) uncontaminated by human activities other than normal agricultural practices were collected and analyzed for 63 major and trace elements using a newly developed high-resolution inductively coupled plasma mass spectrometry method. Sample handling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. Mean concentrations of the elements (micrograms per kilogram of fresh weight) were compared with those reported previously from other surveys. The results provide useful biological and nutritional information on onions.