In a 32-year-old women with clinical and scintigraphic signs of thyroiditis, serological screening showed positive IgG and IgM titres against Parvovirus B19 (PB19). Subacute thyroiditis has not previously been reported following PB19 infection. The present case suggests that subacute thyroiditis may be caused by PB19 infection. Further screening is necessary to establish whether this infection is more frequently associated with subacute thyroiditis than previously thought.