The 40 year-old woman was among zoo workers loading three elephants - one male and two females - into a truck in order to transfer them to a zoo in Valencia, Spain. She had been working with the animals for almost 10 years.
A female elephant attacked the woman when she approached the male, breaking the woman's neck with a single blow of its foot, killing her immediately.
While this is the first such event in the history of the Moscow Zoo, a number of similar incidents have been reported in zoos in former Soviet republics in recent years.
In 2005, in Kiev Zoo, in Ukraine a tiger killed a cleaner, while in the same year, in Alma-Ata, in Kazakhstan, a visitor to the city zoo had his hand bitten off by a lion.
The Prosecutor General's office has begun a probe into the accident to decide whether a criminal investigation should be launched.