Tourist arrivals had dropped 20 percent over the 10 months to October to 387,790 compared with the same period last year, Sri Lanka Tourism said.
October's arrivals were 4.6 percent lower at 37,011 compared with the same month in 2006.
Overall earnings for the industry fell 16 percent over the nine months to September compared with the same period a year earlier.
Tourism is Sri Lanka's fourth-largest earner, after garments, remittances from overseas workers and tea.
The drop in tourist numbers comes after a year of intensifying fighting between the government and the Tamil Tiger rebels.
The war is mostly in the north and east, far from the island's southern holiday beaches.
But the guerrillas this year managed to hit the capital, Colombo, and its international airport.
Analysts expect the war to escalate with Colombo convinced it has the upper hand in the 35-year-old ethnic conflict.
The government unveiled the nation's biggest-ever war budget earlier in November.
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