Fusobacterium necrophorum is a Gram-negative anaerobic bacillus that can be a primary pathogen causing either localised abscesses and throat infections or systemic life-threatening disease. Systemic infections due to F. necrophorum are referred to as either Lemierre's disease/syndrome, post-anginal sepsis or necrobacillosis, but in the context of this mini-review, all are included under the umbrella term of 'invasive F. necrophorum disease' (IFND). Although IFND has been well documented for over a century, it is quite a rare condition and modern-day clinicians of various medical disciplines are frequently unaware of this organism and the severity of symptoms that it can cause. IFND classically occurs in previously healthy young people although the factors that trigger the invasive process are not fully understood. There are countless descriptive case histories and small series of cases of IFND disease in the literature and although commonly referred to as a 'forgotten' disease, in truth, it is probably best described as a repeatedly 'discovered' disease, as it may not always be included in medical curricula, and neither is it mentioned in some major medical textbooks. There is some evidence that IFND may be on the increase, particularly in the UK. The potential reasons for this are considered in this review along with an historical overview, and updates on disease incidence, patient demography, pathogenesis and laboratory diagnosis.