Barcelona's civil defence said a 51-year-old German woman had died from injuries sustained in the August 17 attack on the city's Las Ramblas boulevard
Death toll from Spain attacks rises to 16
The number of people killed in twin vehicle attacks in Spain last week rose to 16 on Sunday.
"This morning a 51-year-old German woman died after being treated in a critical condition in hospital," said a statement from Barcelona's civil defence.
Around 120 people were wounded in the attacks on Las Ramblas boulevard in Barcelona and the seaside resort of Cambrils.
The woman who died on Sunday was hurt in the Barcelona attack in which a man ploughed a van through crowds of tourists on Spain's most famous street. The August 17 attack was claimed by ISIL.
Hours later, a car sped into Cambrils some 120 kilometres south of Barcelona, hitting people before crashing into a police vehicle.
The five occupants of the Audi A3 then jumped out and went on a stabbing spree, killing a woman before being shot dead by police.