A body has been found on the Waikato Expressway at Mercer early this morning.
Police said they were investigating the circumstances leading up to the death.
The body was found on State Highway 1 shortly before 3am.
The northbound lane of the expressway was closed while the police serious crash unit examined the scene.
Inspector Kerry Watson of police northern communications said diversions were in place. However, traffic was not heavy and there was no backlog early this morning.
Police were speaking to several motorists and passersby who helped to secure the scene.
Mr Watson said no details of the deceased would be released until next of kin have been advised. That was expected to take some time.