Missing Pahiatua man John Campbell, found in a shallow Wairarapa creek, died from drowning, a post-mortem has found.

Mr Campbell, 64, was last seen leaving his Pahiatua home, in the northern Wairarapa, for work at 6.45am Tuesday.

His body was found in a gully stream on a pine plantation near Hope Road in Woodville, 20km from his home, about 2pm yesterday.

His car, a white Toyota Starlet, had been parked from 7am on Tuesday, about 1km away from where his body was found.

A post-mortem had confirmed Mr Campbell's identity and preliminary results suggested he died from drowning, Sergeant Steve Baddock of Pahiatua said this afternoon.

He was unsure how Mr Campbell had drowned in a shallow stream, but said police were investigating and would be presenting their findings to the coroner, Mr Baddock told NZPA.

Mr Campbell did not know anyone in Woodville and had no known reason to be there, police spokeswoman Kim Perks said yesterday.

He was in good physical health, had no known medical conditions and his disappearance was completely out of character, she said.