A small number of other children are under investigation.
One child has died and two have needed liver transplants.
The Health Protection Surveillance Centre said this number of cases is more than would usually be expected over this period of time.
The children affected have no links to each other.
To date no single virus has been identified in all cases.
Investigations are ongoing to identify the cause of the illness. There are hopes that these cases may have peaked.
All probable cases are in children between the ages of one and 12 years of age, and all have been hospitalised.
In the UK, health authorities have also reported an increase in hepatitis of unknown cause in children.
Information gathered thus far from the UK investigations suggests that the recent cases may be linked to adenovirus infection, but this theory is still being studied.
Adenovirus is a common cause of childhood and adult illnesses, typically resulting in mild cold- or flu-like illness, or diarrhoea. However, adenovirus infections rarely cause hepatitis.
The Irish cases have no links to the UK cases, and only one had a recent history of travel to the UK before onset of symptoms. The common viruses that cause hepatitis (hepatitis viruses A, B, C, and E) have not been detected in any of the cases.
Other possible causes such as another infection (including Covid-19) or environmental factors are also being investigated.
In Ireland, as in other countries, research is under way to determine whether current or previous Covid-19 infection may increase the risk of this disease in some children.
Parents are advised to go to their GP if their child develops symptoms of hepatitis, including pale grey stools, dark urine, yellowing of the skin or eyes, muscle and joint pain, high temperature, nausea and vomiting, and general malaise.