Lemierre's syndrome (or Lemierre's disease) is a disease caused by the bacterium Fusobacterium necrophorum, and usually affects young, healthy adults.

The first symptoms are just a sore throat, but after a couple of weeks this is followed by infections of the blood which can cause complications in the lungs, liver, joints or many other parts of the body if untreated.

Lemierre's syndrome is easily combatted by antibiotics, but because a sore throat is usually caused by viruses, which do not react to antibiotics, such treatment is not usual in the first phase of the disease.

Lemierre's syndrome is currently a very rare disease, but was quite common in the early 20th century before the discovery of penicillin.