Introduction: A cost-minimization analysis (CMA) was performed comparing IVIg and PLEX in the management of patients with exacerbation of myasthenia gravis (MG). Methods: This study combines Ontario-based health costing data with clinical data from a randomized clinical trial where patients with moderate/severe MG received either IVIg or PLEX. The CMA was undertaken under the perspective of a public health care insurer and under the perspective of a tertiary hospital payer. Results: The IVIg group (n=32) was comparable with the PLEX group (n=38) regarding demographics, disease characteristics and severity. PLEX was less costly than IVIg among patients with body mass index (BMI) ≤15.7 Kg/m2, under the perspective of a public health care insurer (CAN$6,271.18 versus CAN$8,309.72, p<0.0001). However, PLEX was more costly than IVIg under the perspective of the hospital payer when the costs of blood products were excluded (CAN$4,815.36 versus CAN$1,486.12, p<0.0001). Conclusions: PLEX may be a short-term cost-minimizing therapy when compared with IVIg for treatment of MG exacerbation among patients with BMI ≤15.7 Kg/m2, under the perspective of a public health care insurer. However, when the costs of blood products are absorbed by a third party, the hospital administration may see IVIg as a more attractive therapeutic alternative.