Iarnród Éireann has imposed an alcohol ban on its 1pm service from Galway to Dublin's Heuston Station due to concerns about anti-social behaviour.
In a statement, the company said the measure follows persistent complaints from customers about regular instances of anti-social behaviour connected to excessive alcohol consumption on the Galway to Dublin service.
No alcohol will be sold by catering staff on the train from this Sunday.
Customers boarding the train in possession of alcohol will have it confiscated.
Iarnród Éireann spokesperson Jane Creegan said there are other routes which have similar restrictions, including certain trains between Waterford and Dublin.
"The decision was taken to make these services alcohol free because we have large groups of people travelling, particularly on stag and hen parties, that may in some instances engage in the over consumption of alcohol and this can be intimidating to other customers."
"It is a measure we take reluctantly, but we must act when our customers are regularly having their journeys disturbed by a minority," she added.