People with missing relatives have marched through London to demand more help from the government.
The mothers of two teenagers who vanished without trace organised the event to highlight the scale of the problem and its effect on families.
The campaigners are calling on the government to give financial aid to a group that provides practical and emotional support.
The Missing People charity estimates 210,000 are reported missing each year.
'Lack of support'
Families on the March for the Missing read out the names of their lost loved-ones and threw a single daffodil to the ground to represent them.
The families are urging MPs to back a Missing Person's Bill to support their aims.
The event was organised by Valerie Nettles, whose son Damien, 16, disappeared from the Isle of Wight in 1996; and Nicki Durbin, whose 19-year-old son Luke vanished from Ipswich in 2006.
The families say while the Missing People charity is "fantastic", it primarily works to find and reunite people. They say there is a need for emotional and practical support for families still searching for lost relatives.
Luke Durbin was last seen on CCTV in Ipswich town centre after leaving a nightclub.
His mother managed to find some support by contacting other women with missing children.
She said: "I felt like I was not dealing with it normally, it is an abnormal, hideous situation.
"You realise you are living parallel lives. You go to work, stay very focused on your job, that life where you behave normally. Then you have this dark world where you just don't know what you are going to do."
Ms Durbin said families of missing people are left in limbo.
"If Luke had died we would have gone through the process of grieving and mourning. But we are stuck and wouldn't think of doing it while we thought there was hope."
The group is also calling for practical support for appeal websites, and to make sure families get as much publicity as possible.
The family of Steven Cook, 20, who went missing on the first night of a holiday with friends in Malia, Crete, faced additional practical problems.
They spent thousands of pounds - much of it raised by their local community - flying to Crete to search for their son.
Steven's father, Norman Cook, said: "If it were people in a lesser financial situation, I think they would really struggle."
He added: "There is a real apathy towards the missing by the authorities, who need to give more support."