BACKGROUND Myasthenia gravis (MG) is an autoimmune neuromuscular disorder, which is often accompanied by various complications. Partial dysgeusia is an uncommon nonmotor symptom of MG, and dysgeusia preceding typical MG symptoms is rare. Although ageusia and hypogeusia have been reported in patients with MG, increased perception of taste has not been reported. CASE REPORT A 47-year-old Japanese woman presented with a reduced perception of sweet taste and an increased perception of salty taste. Meanwhile, she was diagnosed with thymoma-associated generalized MG and underwent extended thymectomy. Three months later, her anti-acetylcholine receptor (AChR) antibody (Ab) titer increased to 70 nmol/L, when she had completely lost perception of sweet taste and had developed a markedly increased perception of salty taste. Prednisolone and tacrolimus were then added to the medication, and her partial dysgeusia gradually improved. As the AChR Ab titer decreased, disturbance of sweet taste resolved, although a slight decrease persisted. The increased perception of salty taste returned to normal. CONCLUSIONS This is a rare case of a patient with MG who developed an increased salty taste perception with a reduced sweet taste perception 3 months before the onset of her motor symptoms. We suggest that MG should be considered as a differential diagnosis in patients with partial dysgeusia but no motor symptoms.