Greenpeace recently hired an independent laboratory, which found phthalates, chemicals used to soften plastic and said to cause hormone malfunctions and reproductive problems, in 21 out of 30 toy samples purchased in four Chinese cities.
The toys that were tested were all produced by mainland Chinese factories, it added.
The European Union and the United States have banned six types of phthalates in children's products and toys, according to the group.
Greenpeace campaigner Vivian Yau, commented: "Governments in the EU and North America have all recognised the serious health concerns of phthalates for children, yet in China and Hong Kong, kids are unprotected from these harmful toxins.
"Children are one of the most vulnerable groups to hormone disruptors -- they like to put things in their mouths, and their reproductive, immune and endocrine systems are still developing."
Greenpeace has since urged Beijing and the government in Hong Kong, to follow the same tack as the EU and North America by restricting the use of phthalates in toys.
The group also called on authorities to usher in a regulatory system to eliminate their use due to the dangers posed to human health and the environment.