Abstract One hundred and six right-handed monolingual Spanish speakers were divided into two groups: (1) general population subjects, and (2) brain-damaged patients. The first group included two subgroups: (a) third-grade school children, and (b) university students with a minimum of 12 years of formal education. The second group was further divided into three subgroups: (a) Broca aphasics, (b) Wernicke aphasics, and (c) right hemisphere-damaged patients. A special writing test was given to each subject. Two types of errors were distinguished: 'homophone' (or 'orthographic') errors and 'non-homophone' (or 'writing') errors. The first type of error was found not only in the abnormal but also in the normal population subjects. In right hemisphere-damaged patients, and also in Wernicke aphasics, homophone errors were significantly increased. The second type of error was observed in the brain-damaged population, and very infrequently in children. No significant correlations between word frequency and homophone or non-homophone errors were observed. The current psycholinguistic models of agraphias were analysed in order to determine their applicability to Spanish language.