The number of people signing on the Live Register in December rose by 7,506 to stand at 166,142, according to the latest figures from the Central Statistics Office.
But when seasonally adjusted, the Live Register total fell from 165,000 in November to 164,700 in December - a fall of 300 - the CSO added.
The unemployment rate last month stood at 4.4%, unchanged from November.
The unadjusted monthly rise on the Live Register reflected increases in all regions of the country, with the biggest increases coming in the Mid-West and the Mid-East. The lowest increases were in the West and in Dublin.
Friends First economist Jim Power said the figures were consistent with the trend of the past 18 months towards a deterioration in the labour market. He warned that this deterioration was likely to be sharper this year because of rising domestic costs, the strength of the euro and a weak global economy.
He predicted a rise from the current rate of 4.4% to 5.2% by the end of the year.