Mr Gargasoulas, 27, appeared via video link before Melbourne Magistrates Court on Friday and entered a plea of not guilty to 39 charges, including six counts of murder.

He waived his right to a pre-trial committal hearing, meaning his case will now go before the Supreme Court on Monday.

With his black hair cut short and beard neatly trimmed, Mr Gargasoulas said "not guilty" when asked by magistrate Simon Zebrowski how he would plead.

He did not say anything else, other than "yes, sir" when asked by the magistrate whether he could hear the proceedings at the start of the hearing.

Defence lawyer, James Yianoulatos, said his client's fitness to plead and mental impairment were "live issues".

In earlier appearances before magistrates, Mr Gargasoulas has made several unprompted rants, including claims he was not guilty and had had a metal breakdown.

Mr Gargasoulas was arrested on January 20, after dozens of pedestrians were hit by a car along Bourke Street, in central Melbourne, at lunchtime.

Six people died, including a three-month-old baby boy and a 10-year-old girl. Dozens of people were injured.

Mr Gargasoulas faces six charges of murder, 28 of attempted murder and one of reckless conduct endangering life, all related to events on Bourke Street.

He also faces charges of intentionally causing serious injury, robbery, making threats to kill and false imprisonment, related to alleged offending in the hours beforehand.

It is alleged he also attacked his brother earlier that day.

The families of some of the people hit on January 20 were in court, along with homicide detectives.

Mr Zebrowski found there was sufficient evidence to commit Mr Gargasoulas to trial after prosecutors tendered the brief of evidence.

No evidence was presented to the court on Friday, and the magistrate refused to release any documents to the media after prosecutors opposed an application by reporters.

He was remanded in custody to appear before the Supreme Court on Monday.

Monday's directions hearing in the Supreme Court is expected to determine how the case proceeds.

Before Mr Gargasoulas appeared on the video link, Mr Yianoulatos told the court he was unsure how his client would respond when asked how he would plead.

Mr Zebrowski told Mr Yianoulatos the accused man's fitness to plead was a potential issue, and said he would have been prepared to enter a plea of not guilty on Mr Gargasoulas' behalf.

But when Mr Gargasoulas appeared before the court and was asked to enter a plea, he responded immediately.

The case has appeared several times before the Supreme Court this year, so Justice Lex Lasry could be updated on its progress.

Justice Lasry has at times expressed frustration at the slow going while the case has been before the courts, and while police were investigating.

The prosecution's brief of evidence includes statements from 900 witnesses.

With AAP