A total of 7242 Victorians - almost 20 a day - went missing in the 12 months to June 30.

And more than 80 per cent were found within 24 hours.

Shattered family members gathered at Federation Square this morning to ask missing loved ones to make contact as the Australian Federal Police launched National Missing Persons week.

Eugene Milograd issued a heartfelt plea for his sister, Tammy, who has been missing for almost 40 years, to make contact.

"Tammy, if you can hear this and see this, please contact us," Mr Milograd said.

"If for whatever reason you feel you can't, let the police know.

"We just dearly want to know that you're alive and well and we're always thinking about you."

Tammy, who was 16 when she vanished, never came home after going to the Royal Melbourne Show with friends on September 18, 1971.

Mr Milograd said the past 39 years had been a nightmare for the family.

"We just feel a bit helpless to do anything about it,'' he said.

"We hear about something and think, `It'll be OK, and then it's a dead end."

Around Australia one person is reported missing every 15 minutes.

Mr Milograd, who now lives in Adelaide, said he believed family tensions with a boyfriend may have triggered Tammy's disappearance.

"But (I) never thought it'd come to something like this, that Tammy would go away and not come back," he said.

"There was some explanation but the length of time is just a nightmare."

AFP Commissioner Tony Negus said filing a missing persons report quickly increased the chances of finding a loved one.

"Research shows there is a myth in society that people need to wait 24 hours before they can report someone missing," Commissioner Negus said.

"This is certainly not the case and the AFP urges people to report a missing person as soon as they become concerned."

 Amelia Harris
    Herald Sun