Acute infectious thyroiditis in patients with ectopic lingual thyroid gland is extremely rare, and in most cases, this condition, if symptomatic, manifests as dysphagia and dyspnoea. This case report shows that, in addition to the previously mentioned typical symptoms, our patient also suffered from febrile temperature, progressive fullness in the throat and pain during swallowing. Diagnosis of acute infectious thyroiditis associated with lingual thyroid gland is complex and requires evaluation of results of clinical findings and laboratory tests, and also evaluation by radiological diagnostic methods. Treatment was performed by administering antibacterial and anti-inflammatory therapy, resulting in the disappearance of complaints. Clinical appearance, diagnostic methods and treatment options are discussed in the discussion section.