The floods were caused by heavy rainfall on Sunday linked to a cold front.
One person was killed while crossing a river in the southwestern department of Grand-Anse, civil defence spokesman Edgar Celestin said yesterday.
The person accompanying the deceased has not been located and three fishermen in the same region have also been reported missing, he added.
Problems linked to the downpours were also reported in the city of Cap-Haitien on the northern coast, where some 8,100 houses were flooded.
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An emergency plan setting up shelters was not activated, meaning that people affected by the flooding have had to seek refuge elsewhere.
The flooding comes just two weeks after Cap-Haitien saw similar fallout from several hours of rain.
Haitian cities are particularly vulnerable to flooding because efforts to reduce the risk are practically non-existent.
More than half the country's population lives in cities but the absence of urban planning has led to urban sprawl, with some structures housing the poor built without permits.