There is concern among some National MPs their party has been overlooked in the recent Cabinet reshuffle.

Prime Minister Malcolm Turnbull's Cabinet was sworn in this morning and included two new positions, both of which were given to Liberals.

The Nationals currently hold seven frontbench positions, including three in Cabinet.

Federal Member for Lyne David Gillespie told ABC Rural his party should technically have gained an extra seat in the Cabinet.

He said the Nationals were entitled to 3.59 seats in the Cabinet and the Liberal Party was entitled to 17.4, rather than the 18 it has now.

"There has been a little bit of an oversight because the convention of the Liberals and Nationals in Coalition in Cabinet is on a percentage basis and on that basis, the Nationals are actually entitled to just under four positions," he said.

"Given that the Prime Minister has now expanded the Cabinet from 19 up to 21, one would've expected four positions.

He called on Mr Turnbull to consider appointing an extra Nationals MP or Senator to the Cabinet in the future.

"If that opportunity arises, I think that would be the logical opportunity to take and improve the strength of the Nationals in the Cabinet," he said.

Last week, the Nationals called the Coalition deal struck between the parties a "win".

The agreement included giving the deputy Nationals leader and Agriculture Minister Barnaby Joyce responsibility for water.

Many senior Nationals deeply dislike Mr Turnbull based on the way he acted on carbon pricing when opposition leader in 2009, but Dr Gillespie said his concerns were not a sign the relationship was already under strain.

"I'm making my observations. Our PM Malcolm Turnbull is a Coalitionist and he proved this [last] week with our agreement," he said.

"We'll get on fine. We want to have good, strong Government with good representation across the country and getting policies out there."