No one has ever been charged over the "Tynong North murders" of six women in Melbourne from the 1980s, but a new $6 million reward could help police catch one of Victoria's most notorious serial killers.

The six murders occurred over 16 months in the early 1980s, with the bodies of four women found in Tynong North, and the bodies of two other women found in Frankston North, in southeast Melbourne.

Victoria Police on Saturday said it is offering six $1 million rewards for information that would help investigators find who killed the women.

All victims were on foot and most had plans to travel using public transport when they disappeared.

Police say whoever dumped the women's bodies had made efforts to conceal the victim's identities and location.

Their personal belongings had also been removed.

The first victim, 59-year-old Allison Rooke, was planning to catch a bus to the shops when she was last seen leaving her Frankstown North on May 30, 1980.

Her body wad discovered weeks later in scrubland on July 5, 1980.

The bodies of two other women who disappeared within weeks of each other were later found with a third victim in scrubland in Tynong North in December that year..

Bertha Miller, 73, left her Glen Iris home to catch a tram to attend Wesleyan Methodist Church in Prahran on August 10, 1980.

Weeks later, 14-year-old girl Catherine Headland disappeared after she left her boyfriend's Berwick home on August 28, 1980 to catch a bus to the Fountain Gate Shopping Centre Narre Warren.

This was followed by the disappearance of Anne-Marie Sargent, 18, after she left her mother's Cranbourne home on October 6 to catch a bus to Dandenong.

All three women's bodies were located after a group of men found human remains near a quarry in Tynong North on December 6, 1980.

The body of the fifth woman to disappear was not found until 1983.

Narumol Stephenson, 34 was last seen outside a friend's home in Park Street, Brunswick in the early hours of November 29, 1980.

Her remains were located after a man changing a tyre off the Princes Freeway in Tynong North on February 3, 1983 noticed a bone sticking ouf of the bush.

Joy Carmel Summers, 55, was last seen at a bus stop in Frankston on October 9, 1981.

Her body was later found in scrubland in Frankston North on November 22.