Last year the company received 277 complaints, up from 258 in 2020.
Several were related to drunken and aggressive behaviour and people not- wearing facemasks.
Drug use was also the focus of complaints, with one woman travelling from Dublin to Cork with her family, describing how a man sitting opposite them took cocaine for the entire journey.
Irish Rail Spokesperson Barry Kenny insists action is being taken to tackle the problem:
"We have more patrols now, in both our own security patrols and joint patrols with Gardai on routes, where there are reports, issues like you know, drug abuse or abuse. We have actually had a number of arrests for example on the Dublin to Cork route where again those reports have been given to us."
