A published confirmatory method for the quantitative determination of four ionophoric coccidiostats (lasalocid, monensin, salinomycin and narasin) in eggs and broiler meat has been further developed. It is proposed for replacement of liquid chromatography methods previously used in analysis of ionophoric coccidiostats. The samples were extracted with acetonitrile and purified on a silica solid phase extraction column. Purified samples were analysed by liquid chromatography-mass spectrometry and the method, was validated according to the Commission Decision 2002/657/EC. The validation parameters selectivity, linearity, specificity, precision, recovery, decision limit (CCalpha) and detection capability (CCbeta) were determined. The recoveries of coccidiostats analysed ranged from 64-99% in eggs and 62-100% in broiler meat. CCalpha varied from 0.8-1.4 microg/kg in eggs and from 1.5-2.5 microg/kg in broiler meat. CCbeta varied from 0.9 microg/kg to 2.0 microg/kg in eggs and from 1.7-3.2 microg/kg in broiler meat.