Four people from the same family in Co Clare are being treated in hospital after testing positive for the coronavirus.
Health officials on Wednesday night confirmed there had been four new cases in the western part of Ireland - bringing the total number of cases in the Republic.
The Health Protection Surveillance Centre (HPSC) says all those affected had travelled from the same area in northern Italy.
Dr Tony Holohan, chief medical officer with the Department of Health, said: "We can confirm there are now six cases of COVID-19 in Ireland.
"Contact tracing is underway for these four new cases."
Dr Ronan Glynn, deputy chief medical officer, added: "There is still no evidence of widespread or sustained community transmission in Ireland, as seen in some other EU countries.
"While we now have six confirmed cases of COVID-19 in Ireland, we continue our containment efforts, central to which is that the public know what to do in the event they have symptoms."
These latest cases follow on from two more confirmed in Northern Ireland earlier on Wednesday.
The region's Public Health Agency said this brings the total there to three cases.
COVID-19 is spread through close contact with an infected person's body fluids - for example, droplets from coughing or sneezing.
It is also spread by touching surfaces that an infected person has coughed or sneezed on.
The Department of Health says this is one of the reasons why it is so important that people wash their hands regularly, practice respiratory etiquette and try to avoid touching their face.
Overall there are 3,199 deaths across 77 countries - 12,744 of the cases are outside of China.
In Europe there are 2,502 cases in Italy, 240 in Germany, 212 in France, 151 in Spain and 87 in the UK.
Thirty-six new patients in Britain tested positive on Wednesday - its biggest daily increase in coronavirus cases.
Any person concerned that they may have symptoms should immediately isolate themselves from others and contact their GP by phone.
More information can be found here.
Reporting by Jack Quann, Stephanie Rohan and Stephen McNeice