Amy Forde, 25, from Uckfield, raised more than £3,000 for the Dr Hadwen Trust (DHT) by completing last Sunday’s Paris marathon.
The DHT is the UK’s leading non-animal medical research charity.
Amy initially hoped to raise just £500 but is now delighted with the total.
She said: “I can’t believe how generous people have been.
“I am thrilled because this is for such a good cause.”
Keen runner Amy has previously undertaken shorter charity runs, including two half marathons, but had never attempted the full distance.
So this was a major challenge, not least because she injured her ankle while training.
She said: “It was much harder than I anticipated.
“I got to 14 miles completely fine and injury free, then it began to hurt.
“From 19 miles I had to limp and hobble the last seven miles.
“I was in terrible pain but what kept me going was the thought that what I was going through was nothing compared to how animals suffer in labs.”
DHT’s Gerry Reilly said: “Funding innovative research which replaces animals is only possible by donations we receive from people like Amy.
“Her effort, literally going through the pain barrier, is astonishing.”
Visit: https://www.justgiving.com/Amy-forde1 or: www.drhadwentrust.org