Diphtheria is a nearly eradicated disease in Sri Lanka. After introduction of EPI vaccination program in 1978 childhood diphtheria has been eradicated. However sporadic cases of adult diphtheria have been reported among the non-immunised adult population. Classical presentation of active severe exudative pharyngitis, and cervical adenitis associated with acute neurological deficit with clinical response to anti-diphtheria toxin makes adult diphtheria a probable clinical diagnosis in the patient. However, isolation of Corynebacterium diphtheriae from the throat of a patient is required for definitive diagnosis. The need for a prepared laboratory system is discussed.