Statistics New Zealand says the number of people staying in hotels, motels, backpacker accommodation and holiday parks fell 6% in May.
It follows a 1% increase in April.
The drop was largely due to fewer overnight stays by domestic visitors, which were 10% lower than in May last year.
International guest nights were largely unchanged.
Hotel patronage rose 3% during the month, but motels, backpackers and holiday parks all had fewer guests.
Guest nights fell 9% in the South Island and 4% in the North Island.