Two National MPs - Hunua's Paul Hutchison and list MP Cam Calder - are retiring from politics at next year.
Calder, based in Manurewa, has just revealed he will not seek re-election at the general election.
Calder, 59, said it was "a huge privilege" to serve in the Government.
"It has been an exciting and extraordinarily varied experience, and I still relish every day, but after two terms in Parliament there are a number of projects, both in New Zealand and overseas, that I wish to consider in the years ahead," he explained.
A former dentist, he entered Parliament in 2009 after the resignation of minister Richard Worth.
Five-term Hunua MP Hutchison also confirmed he would not seek re-election.
A former consultant with 30 years in medicine, 65-year-old Hutchison was first elected to Parliament in the Port Waikato seat in 1999, and was returned in 2002 and 2005.
In 2008 and 2011 he was elected as the MP for the new Hunua seat.
He brought his medical experience to politics, as Opposition health spokesman and chair of the Health committee.
Hutchison said today he told Prime Minister John Key of his decision a year ago.
The father of four said: "I look forward to spending more time with my family, including my two younger girls aged 12 and 13. I am also excited about the prospect of future professional opportunities in New Zealand or overseas."
Hutchison said he was proud of increasing his majority at each election from 3915 (43.2 per cent) to 16797 (64.3 per cent) in 2011. He had also initiated five select committee inquiries on disability services, immunisation, prostate cancer, clinical trials, and innovation.
"These have seen positive policy changes."
Internal affairs minister Chris Tremain and West Coast list MP Chris Auchinvole announced earlier this month they would not seek re-election.
Sources said more were expected to go, as the party leadership wanted to rejuvenate and inject more new blood in preparation for the election.
Others tipped to be considering their future are Waimakariri MP Kate Wilkinson and Waikato's Lindsay Tisch.
Both Wairarapa's John Hayes and Kaikoura's Colin King were also facing looming battles for selection in their electorates.
Does David Cunliffe need to resign as Labour leader?Related story: David Cunliffe's leadership on the line