More than 20 KiwiRail services in Wellington are affected on Tuesday afternoon due to staff illness.
The 24 services affect trains travelling to Melling, Taita, Porirua and Johnsonville.
A spokesperson for KiwiRail says 10 services will be replaced by buses.
The other 14 are cancelled, with the Waikanae service picking up those passengers.
KiwiRail was unsure whether it would cause major delays.
