The six year old boy in Olot (Catalonia) who became ill with diphtheria died overnight at the Vall d'Hebron hospital in Barcelona, a spokeswoman for the Catalan regional health authorities confirmed to The Spain Report by telephone.
He had not received anti-diphtheria vaccinations.
The young boy was admitted to hospital 28 days ago after it was confirmed he was suffering from the first case of diphtheria recorded in Spain since 1987.
An anti-toxin treatment was rushed to Barcelona from Russia but proved ineffective.
The boy's parents felt "terribly guilty" and that they had been "tricked" by anti-vaccine groups who convinced them not to vaccinate their son, the public health secretary in Catalonia said during a press conference on June 5.
By June 8, it was reported the boy was being kept alive on life support machines in the hospital's intensive care unit.
During a screening process following the boy's infection, health authorities in Catalonia discovered eight more children were carrying diphtheria bacteria, but had not developed the disease because they had been vaccinated.