New figures from the Central Statistics Office show that prices were 0.3% lower in September compared with September of last year on the back of cheaper transport and clothing costs.
On a monthly basis, consumer prices fell by 0.5% in September from August, their biggest monthly fall since January.
Today's CSO figures show that transport costs fell by 5.5% on an annual basis due to lower petrol and diesel prices and a reduction in the price of cars.
However, these drops were partially offset by an increase in bus and taxi fares.
Clothing and footwear prices eased by 4% due to sales in shops while the cost of food & non-alcoholic beverages fell by 2.2% due to lower prices across a range of products such as meat, bread and cereals and vegetables.
However, education costs rose by 5% on an annual basis in September.
The cost of miscellaneous goods & services - which includes such things as insurance, hairdressing and cosmetics and skincare products - also increased by 2.8% with a 26% jump in motor insurance premiums noted.
Commenting on today's figures, Merrion economist Alan McQuaid said that despite the booming economy, inflationary pressures are likely to remain fairly well contained in the immediate future, mainly because of lower oil prices.
But he cautioned that the cost of services like insurance look set to continue to rise.
Mr McQuaid said the issue of deflation is not seen as a major issue here.
"Low inflation in Euroland will mean easier ECB monetary policy being in place for longer, which should be good news for consumers, though whether it feeds through into lower variable mortgage rates here remains debatable," he added.