In a letter to The Telegraph, signatories wrote: "We believe such proposals devalue the most vulnerable in society."
They stressed how doctors often have to see patients who feel a burden to their loved ones and warned against the pressure this could have on vulnerable people to take their own lives: "they may be under pressure from within to remove themselves as a burden on their hard-pressed families.
"We fear that if Parliament were to legalise assisted suicide for terminally ill people, such pressure would be given free rein.
"Most families are loving and caring, but some are not."
The collective of doctors said that they are worried this change in the law could exert unwanted pressure on terminally ill people to end their lives against their will.
"We have a duty to do no harm and a duty of care to patients, and I think this would drastically change the doctor patient relationship," said Dr Melody Redman, one of the letter's signatories on Premier's News Hour.
"I just feel that doctors would put in a very difficult position and a lot of doctors wouldn't want to be involved," added Dr Redman.
This letter comes after an alliance of bishops, priests and rabbis from spoke out from their religious groups in support for plans to change the law, earlier this month, arguing that helping the terminally ill should be viewed as enabling someone to "gracefully hand back" their life to God.
The opposed doctors say the proposed law is built on the idea that assisted dying will relieve the suffering of ill patients - however they go on to say that medical advances have transformed the way people die and can offer a huge amount of pain relief.
"Assisting suicide runs counter to our duty of care, is contrary to the "do no harm" principle and conflicts with policies for suicide prevention," they wrote.
Signatories include Dr Sarah Annettes, Dr Roger Boyle and Dr Phil Williams.
The bill is due to be debated in parliament on 11th September.
The Marris Bill mirrors proposals suggested by Lord Falconer last year, but adds that people thought to have no more than six months to live, who have a "settled intention" to end their life, could be given a lethal dose of drugs on the agreement of two doctors, as well as a judge.
Most recently 68-year-old Bob Cole from Cheshire pleaded with MPs to support the bill, before taking his own life at the Dignitas clinic in Switzerland.
Listen to Dr Melody Redman speaking to Premier's Hannah Tooley on Premier's News Hour:
