One hundred and seventy-five aphasic patients (50 total, 50 mixed, 50 motor-amnesic and 25 sensory-amnesic aphasics) were tested for the writing to dictation of numbers with more than one digit. Twelve types of error were found. The percentages for the different types of error were determined for all subtypes of aphasic patients and for the total group of patients. In 98% of the aphasic subjects at least one or several types of error were ascertained. In all, 80.6% of the patients were unable to write correctly a number of three digits. Certain types of disturbances, such as macrographia, serial writing, perseveration and mirror writing, occurred more often when numbers were dictated than when words or letters were dictated. In the patients with sensory-amnesic aphasia these disturbances were found more often than in those with motor-amnesic aphasia. With respect to German-speaking patients, a particular type of error concerns the serial ordering of numbers with more than one digit (Stellenwertfehler). This type of error was found in 34.9% of our patients. Our results suggest standard examinations of aphasic patients should include the writing to dictation of numbers with more than one digit.