Late-night weekend train services in Perth are to be cancelled because not enough people are using them.

The late trains are a free service departing the city on all lines at 1.00am or 1.15am, and 2.15am on Saturday and Sundays.

The last train on each line would now leave Perth about midnight on weekends, the same time as weeknights, Transperth said.

"The numbers vary considerably, seasonally and from line to line," Transperth spokesman David Hynes said.

"However we're talking about an average of around 80 passengers per train, and some are only carrying 20 to 30 passengers.

"Public transport in WA is already heavily subsidised by the State Government to the effect of about 70 per cent.

"Though journeys on these late trains are free, each passenger costs the taxpayer more than $17, significantly higher than the average train passenger subsidy.

"On average, it's somewhere between $2 and $4 per person a subsidy so $17 per person is way over the mark."

Cutting the services would save about $6 million over the next four years, Mr Hynes said.

"Given the level of subsidies that has to be made, even for ordinary public transport, when that rises to something like $17 a person, it's just not sustainable.

"So, we're going to take the resources that we're putting into that which comes to about $6 million over a four year period, and put those resources to where they'll be better used."

When asked whether the lack of train services would put more drink-drivers on the road, Mr Hynes said Transperth was liaising with the police, City of Perth and the Northbridge business sector to let them know the service was ending.

"Our job is to provide public transport and use the taxpayer dollar in the best way we can and clearly providing this service is just not economically feasible, not enough people are using it," Mr Hynes said.

The late-night trains will cease after the Easter long weekend.