Milroy's disease (MD), also known as hereditary lymphedema type I, is a rare autosomal dominantly inherited primary lymphedema. It accounts for approximately twenty percent of all primary lymphedemas. MD typically presents clinically with bilateral lower extremity lymphedema. Our case report is about a rare case of MD presenting with unilateral lymphedema in both upper and lower extremities in a patient admitted to our clinic. A 24-year-old woman who had been under observation for lymphedema since she was 8 years old was diagnosed with MD by physical examination, venous Doppler ultrasound, whole body lymphoscintigraphy, and molecular genetic testing in our clinic, and partial improvement was achieved with Complete Decongestive Therapy, the gold standard treatment for lymphedema. Genetic counseling services may be especially useful for the patient and family. Although MD is rarely seen in the literature, many more studies are needed to identify carrier variants in the community.