Typhoon Mekkhala battered central Vietnam early on Tuesday, triggering floods and leaving at least nine people dead in its wake, media reported.
Another 11 people were declared missing in the storm, which later weakened into a depression, said public television VTV.
The victims were either swept away in floods resulting from the storm or disappeared at sea, VTV reported.
Eleven boats have also gone missing.
The typhoon struck one week after another storm, Hagupit, left 45 people dead.
Hundreds of people die in storms and flooding in Vietnam every year, typically during the wet season between July and November.