"After the judge read out the charges, the five pleaded not guilty and walked out," said AP Singh, a lawyer defending two of the accused, Vinay Sharma and Akshay Thakur.
Singh said the prosecution will call three witnesses to the next hearing on Tuesday, which is the formal start of the trial. The prosecution says it has strong evidence against the five men including blood stained clothing, DNA matches, mobile phone records, confessions and eye-witness statements.
Singh says Sharma was never on the bus and Thakur was hiding beneath a seat and never took part in the crime.
The other men - brothers Ram and Mukesh Singh and Pawan Kumar - are represented by two other lawyers. Mukesh Singh has replaced a lawyer who claimed his client was tortured in police custody, and no longer claims mistreatment.
A sixth person police say was part of the gang that attacked the woman and her friend is a juvenile and will be tried separately.
The brutality of the attack shocked the nation to such an extent that it brought thousands of young protesters to the streets in the weeks that followed. In response to the public outcry, on Friday the Union Cabinet fast-tracked new, tougher penalties for sex crimes.
(With agnecies inputs)