Pellucid marginal corneal degeneration is a bilateral disease characterized by a narrow band of corneal thinning localized 1-2 mm from the inferior limbus. The disease is diagnosed usually between 20 and 50 years of life, and its etiology remains obscure. During the clinical course and evolution of pellucid marginal corneal degeneration, acute hydrops with corneal edema in the lower half may develop (acute pellucid marginal corneal degeneration). However, since cases of acute pellucid marginal corneal degeneration are not frequently encountered in clinical practice, each new patient is evaluated and managed with the utmost care to contribute to our better understanding of this disease. This is a report of two cases of acute pellucid marginal corneal degeneration that had a relatively favorable functional outcome when treated medically, so that corneal grafting was not necessary.