6 percent to 37,104 compared to the same period in 2006.
The drop for the first nine months to September was 21 percent to 350,779, Sri Lanka Tourism (SLT) said.
SLT said there was "no cause for alarm" despite two rebel attacks in the past week at a wildlife park in the southeast and Monday's deadly ground and air attack on the Anuradhapura military base.
Located 210 kilometres (130 miles) north of the capital Colombo, Anuradhapura is an ancient sacred Buddhist city and major attraction.
"There is no direct impact on tourists or tourism operations from this incident... there is no cause for alarm for the tourism industry," said SLT Additional Director General, Dileep Mudadeniya.
Cultural tours account for about 10 percent of the island's hotel bookings, and tour operators are cautious as many countries have only recently eased travel warnings.
A number of foreign embassies have advised their nationals to avoid travel