SARS-CoV-2 infection often causes neurological symptoms and complications. Those associated with the production of antiacetylcholine receptor antibodies are rare. The aim of the study was to present a case of transient myasthenia gravis as a possible complication of COVID-19. A 1.5-year-old boy was admitted on day 7 of varicella due to poor general condition and anuria. On examination, he presented with dehydration, fatigue, sleepiness, and bilateral ptosis. High titre of serum anti-SARS-CoV-2 antibodies was revealed with a history of viral infection 2 weeks prior. An initial diagnosis of encephalitis was made and treatment was started. Despite clinical improvement, gait disturbances and ptosis persisted and the boy was sent for further neurological evaluation. High titre of anti-acetylcholine receptor antibodies (2.98 nmol/L; normal <0.50 nmol/L) confirmed myasthenia gravis, but no treatment was started. Symptoms and antibodies resolved after 3 and 4 months, respectively. A follow-up after one year showed no recurrences. Conclusion: Transient, self-limiting myasthenia gravis may develop in a child as a complication of viral infection, including COVID-19.