Underbelly Razor, which stars Chelsie Preston Crayford and Danielle Cormack, has been labelled too "explicit" after research from Fusion Strategy found that 79,000 boys aged 0 to 15 and 67,000 girls aged 0 to 15 watched the brutal first episode of the crime drama.
The fourth season of the Australian show tells the story of the underworld gang wars in Sydney in the 1920s and features graphic sex scenes, murder, weapons, drug-taking, prostitution and domestic violence.
Psychologist Dr Janet Hall told The Daily Telegraph: "Young folk have sensitive brains and could be taking on very negative messages by watching Underbelly.
"They are learning that criminals often get away with violence and even that it is entertaining to live a violent life. They are watching sex scenes which are far too explicit and provocative."
A Nine Network spokesperson said that they screen appropriate warnings before each episode, so it was "up to the parents on how they exercise control at home".
Crayford recently revealed that she and Cormack became "incredibly close" during filming. She also said that she based her character on Amy Winehouse.
Watch the trailer for Underbelly: Razor below (contains shocking images):