New Central Statistics Office figures show a rise in the seasonally-adjusted surplus in May to €5.226 billion - the second-highest on record - and up from the revised surplus of €4.359 billion in April.
The CSO said that seasonally-adjusted exports were up 5.1% in the month at €11.675 billion while imports fell by 5% to €6.449 billion.
Today's figures show that exports of medical and pharmaceutical products jumped by 54% to €4.439 billion in May compared to the same time last year.
But exports of organic chemicals decreased by 12% to €1.807 billion and exports of electrical machinery fell by 24% to €363m
Meanwhile, imports of mineral fuels imports rose by 23% to €450m in May, while imports of machinery specialised for particular industries increased jumped 51% to €195m and imports of other transport equipment, including aircraft slumped by 37% to €1.203 billion.
The CSO noted that exports to the UK fell by 10% to €1.182 billion in May of this year, mainly due to a decrease in exports of chemicals and related products with a smaller decrease in exports of machinery and transport equipment.
Exports to the UK for the five months from January to May stood at €5.527 billion, down 8% when compared to the first five months of 2017.
Imports from the UK also decreased by 6% to €1.522 billion in May compared with the same month last year on the back of a lower level of chemicals and related products imports.
UK imports for the five months from the UK totalled €7.258 billion, up 3% when compared to the same time in 2017.
The CSO said the EU accounted for €5.668 billion (48%) of total goods exports in May of which €1.363 billion went to Belgium and €701m went to Germany.
Total EU exports in May increased by 1% on the same time last year.
The US was the main non-EU destination accounting for €3.205 billion (27%) of total exports in May of this year,
Meanwhile, the EU also accounted for €4.193 billion (62%) of total goods imports in May, an annual increase of 3%.
The US and China were the main non-EU sources of imports in May, the CSO added.