A single case study of a patient, ROH, who had a space occupying lesion in the left frontal lobe is reported. His selective speech disorder had all the hallmarks of a dynamic aphasia. Tests of sentence completion, phrase generation and sentence generation were administered. His ability to generate sentences was significantly better given a pictorial context than a verbal context. Although he could order a sequence of pictures, he had the greatest difficulty in ordering the constituent words of a sentence. Luria's hypothesis that dynamic aphasia is due to an impairment of inner speech which provides "the linear scheme of a sentence" is discussed. It is concluded that dynamic aphasia does not reflect a deficit of language processing but rather the selective impairment of verbal planning.