The state-owned railway said it recorded 8.5 billion passenger-kilometres in the first half of 2012, compared to 8.7 billion in the same period a year earlier.
A passenger-kilometre is a way of measuring performance by multiplying the number of passengers by the distance travelled.
Profit from the passenger sector fell by a third to 65 million francs, according to information confirmed by SBB after reports by Sunday newspapers Le Matin Dimanche and SonntagsZeitung.
The rail company attributed the reduction in passengers — more than two percent from the figures provided — to the ongoing slowdown in the tourism sector.
SBB spokesman Reto Schärli said regional traffic remained stable while rail travel for pleasure dipped nationally.
Steady sales of rail passes indicate that customers continue to count on the train to make daily trips, Schärli said.
“Sales of half-fare cards and general (annual) passes increased, even though the costs for these increased,” he said.
No precise details of the increases were released.
The SBB is set to publish official results for the first six months of the year on Wednesday.
The rail company said it carried an average of almost a million passengers a day in 2011, a 2.7 percent increase over the previous year.
(Incorrect passenger-kilometre figures were provided in an earlier version of this article.)