The aim of this work was to determine the concentrations of some essential and toxic elements in the muscle of ten species of commercial fish consumed in Portugal. We combined two different techniques for determination of the elements--energy-dispersive X-ray fluorescence (EDXRF) was used to quantify K, Ca, Fe, Zn, Se, Rb, and Sr and flame atomic-absorption spectrometry for analysis of Cr, Ni, Cu, Cd, Hg, and Pb. The latter technique was used because of its higher sensitivity, because these elements were not detected by EDXRF. The results obtained show a similar pattern for the trace elements. K and Ca are present at the highest concentrations in all the samples studied, from 0.6-1.3% and from 0.04-0.08%, respectively, followed by Zn, Fe, Sr, Se, and Rb. Sr is present at higher concentrations than Rb in all the species studied except meagre. Concentrations of the elements in octopus do not follow this pattern--Fe is present at a higher concentration than Zn. Low concentrations of Cr (0.66-1.5 microg g(-1)), Ni (0.11-0.24 microg g(-1)), Cd (0.01-0.08 microg g(-1)), Hg (0.49-2.74 microg g(-1)), and Pb (0.02-0.06 microg g(-1)) were observed in all the samples analysed. The concentration of Hg was highest in Helicolenus dactylopterus--5.4 microg g(-1) in one sample.