AIB says the Irish service sector has "collapsed" in the past month, with an unprecedented drop in business activity.
The bank's monthly survey of firms in hospitality, transport, leisure and financial services has plunged to its lowest level in 20 years.
Oliver Mangan, chief economist at AIB, says this should be a short, sharp shock.
But he says it's not clear if strong growth levels will return.
"Whether or not it gets back into the levels we saw in February may be debatable, but certainly we'll be back in growth territory very quickly.
"This is not your typical recession, where you slide into recession and spend a long time in recession and then you drag yourself out of it.
"What we're seeing here is an incredibly steep contraction which is likely to last for a short period of time, followed by a strong rebound."
