Tony Nicklinson, 57, is almost completely paralysed and communicates through a specially adapted computer which records blinks and tiny head movements.
[Related article: Tony's story so far]
Earlier this year the father of two from Wiltshire won the right to ask a court to declare that a doctor can end his life. The full hearing is due to take place later this month.
In a personal statement to the court, the former rugby player spoke of being “fed up” with the “indignity and misery” of life almost seven years after suffering a stroke during a business trip to Greece.
Describing his helplessness, he added: “I cannot scratch if I itch, I cannot pick my nose if it is blocked and I can only eat if I am fed like a baby – only I won't grow out of it, unlike the baby.”
But now Mr Nicklinson has been persuaded to join the social networking site to help him communicate with a broader audience and follow and join debates.
In a message posted just after 3pm today he wrote: “Hello world. I am tony nicklinson, I have locked-in syndrome and this is my first ever tweet. #tony”
His daughter Lauren followed a few moments later with a message reading: “Hi Dad! Very proud you are managing to work twitter! See you tomorrow evening. Love Lauren xx” Within two hours he had 147 followers.
Mr Nicklinson’s wife Jane said that it had been relatively simple to connect his specially adapted computer to the site.
“He has never been one to be shy with what he says, this is something where he can do that,” she said.
“He had to be coaxed in to doing it and I hope he will continue, I think it might be good for him.
“We know that there might be people on there who are very vocal about how they disagree [with him] but we are prepared for that.”
The crew from a Channel 4 Dispatches programme in which he is due to appear helped set the account up, she explained.