The objective of this work was to quantify the impact of the voluntary fortification of foods on dietary intakes of vitamins and minerals of Irish adults. Foods that were voluntarily fortified were identified and pre- and post-fortification levels of micronutrients were determined from data supplied by manufacturers and food composition tables. Using food consumption data in 1379 adults aged 18-64 years, estimated using a 7-d food diary during the North/South Ireland Food Consumption Survey, intakes of micronutrients were determined, both including and excluding the fortification component in foods. Of approximately 3000 foods recorded as consumed, 1.9% were fortified, mainly breakfast cereals and beverages. Median micronutrient content of fortified foods (FF) ranged from 18-33% EC RDA per typical serving. Among consumers(65% of men, 68% of women), FF contributed, on average, 3.9% (men) and 5.0% (women) to mean daily intake (MDI) of energy. Relative to their contribution to MDI of energy, FF contribute a greater % MDI for Fe (men 16, women 19), folate (men 18, women 21), vitamins 131 (men 14, women 16), 132 (men 16, women 18), 136 (men 12, women 15), D (men 5, women 11), B 12 (men 5, women 7) and niacin (men 10, women 12). Fortification significantly improved the adequacy of intake of some micronutrients, particularly of riboflavin, folate, vitamin D and Fe in women and did not contribute to an increased risk of adverse effects from excessive intake of any micronutrient.