The HSE hired 34 mental health staff this year, but still has a staff shortfall of more than 2,400.
The health service estimates it would cost €194m per year to increase the number of staff to the recommended level.
Kildare and parts of Dublin and Wicklow had fewer than half the staff required to adequately serve the population in those counties.
Fianna Fáil Deputy James Brown, who obtained the figures from the HSE, said the Government was not prioritising mental health.
He said: "We see only 34 staff being hired in our mental health services between January and October this year.
"When you see 2,500 staff shortage in our mental health services, it's totally unacceptable.
"The Government is simply not giving the mental health services the priority it deserves, and (not giving) patients the care they desperately need."