GWENT service families say they are disgusted at the revelation that tissue samples from service men and women have been kept without their relatives' permission.
The Ministry of Defence (MOD) has apologised after the discovery was made in July and is investigating.
Around 60 samples, taken from about 30 people, are thought to have been kept beyond the time it was needed for evidence in inquests and Special Investigations Branch investigations but without the permission of relatives.
The MOD said it is in the process of contacting the families involved.
For the family of an Abergavenny serviceman killed after serving in Afghanistan in 2009 they say they now face an agonising ten day wait to find out if they are involved.
During that time the family of Private Richard Hunt will also have to mark the third anniversary of the 21-year-old's death on August 15.
Pte Hunt's mother Hazel Hunt said : "I think it's absolutely appalling. Being the Special Investigations Branch they more than anybody should know that you don't break procedures. All the families are still grieving and trying to move on with their life then something like this happens and you're left in limbo gain."
She said: "I just hope and pray that we aren't one of the families involved and feel dreadfully sorry for those that are."
Mrs Hunt added: "You feel like you might just be getting an edge on your grief and move on with your life and they go and do something like this."
Sarah Adams, whose son Private James Prosser was killed in September 2009 while serving in Afghanistan, said: "I am absolutely stunned and to think it might be a part of James. What must the parents think? Have these guys not done enough?
"I don't understand why any doctor would think it was correct to keep something in that way. If a post mortem has already been done then they already know what happened. Why would you not say, out of respect for that family, would you mind if we do this."
John Adams' son Private Kyle Adams, from Cwmbran, was killed in Afghanistan three years ago while serving with the Parachute Regiment.
Mr Adams, from Cwmbran, said: "It's disgusting. I don't think my son is involved but I really feel sorry for those families who have to go through this."
He added: "To me, it's devastating. How can it happen? To bury your son and then to find out part of your son is left behind."
Families involved can contact a helpline set up by the MOD on 01980 673707 and 07771 704901.