Speech delay is known as a relatively late start of speech which has a typical pattern of development. Speech delay with an unknown cause is a problem in children. These children exhibit normal findings in routine auditory tests and also show no findings in their test by a neurologist, indicating autism and similar disorders. Treatment should begin as soon as possible, but the dilemma in the diagnosis and treatment of speech delay with an unknown cause is the fact that this diagnosis is a last differential diagnosis after observing normal findings in routine hearing tests among this group of patients and also the absence of any neurological causes of speech delay.