Police in Bindura have since launched a manhunt for the suspect, who comes from Musana communal lands.
Mashonaland Central police spokesman Inspector Nicisson Kasoso said the man was allegedly caught raping his sister on Sunday at around 1am.
He said the man knocked on the door of the hut in which his sister was sleeping with her two children, aged eight and 12.
When there was no response to the knock, he reportedly broke down the door with an axe.
On entering the hut, the man demanded 100 pula from his sister, which she gave him.
After taking the money, the man threatened to axe her if she did not comply with his orders.
He allegedly tried to strangle her before dragging her out of the hut and then went on to rape her.
The woman’s 12-year-old child rushed to a nearby homestead and alerted a neighbour.
The neighbour rushed to the scene where it is said she found the man raping his sister.
The suspect fled on seeing the neighbour.
A report was made at Bindura Rural Police Station.