Up to 400,000 people in Ireland have experienced depression, according to Aware.
The group, which helps those with depression, said it had revised its figures upwards, in line with the growth in population.
Aware yesterday launched a campaign to encourage people to recognise the symptoms of depression and to acknowledge that although it is common, it is also treatable.
The organisation runs support groups at more than 60 locations in the Republic for those suffering from the illness and relatives of those affected.
It said yesterday that research it previously commissioned showed such meetings, when combined with other information on depression, were an effective way of coping with the condition and reducing relapse rates, etc.
"The accepted statistical figure is that one in 10 of the population will experience the condition at any one time," it said.
Aware also launched a consumer affairs group yesterday, aimed at vocalising the concerns of service-users and others.
Aware has a loCall helpline on 1890 303302 which is open every day.
For further information, visit www.aware.ie.