Spinal Muscular Atrophy (SMA) type 3 is an autosomal recessive disease that occurs as a result of the degeneration of the motor neurons of the spinal cord and causes severe functional impairment in patients. This case report aims to examine the effects of individual exercise programs on functional performance applied to two siblings with SMA type 3. Siblings were included in an individually planned exercise program for 60 minutes, 2 days a week for 8 weeks. Before and after the exercise program, the motor performance, trunk impairment, gait, balance and activities of daily living were evaluated with Motor Functional Measurement, Trunk Impairment Scale, GAITRite electronic walkway, Bertec Balance Check Screener (TM) force platform system and Functional Impairment Measurement, respectively. The individually planned exercise program had positive effects on motor performance, trunk impairment, gait, balance and activities of daily living in siblings with SMA type 3. An individual exercise program that is planned by the functional status of the patient and includes different exercise types is extremely important to increase the functional independence of SMA type 3 patients during the rehabilitation process.