This paper reports on a clinical observation of 37 cases with a particular type of articulation error which is to be categorized as the nasal articulation. Results of the observation are summarized as follows: 1. The nasal articulation is seen to occur for Japanese syllables with the vowels /i/ and /u/, and also with the consonants /s/ and /z/. The sounds frequently affected are /ki/, /si/, /ci/, /ni/, /ri/, /gi/, /zi/, /su/, and /zu/. 2. Cine radiography of the patients shows an articulatory gesture similar to /i/ with the oral closure using the back of the tongue and the soft palate, the air flow and the sound wave being directed to the nasal cavity. Stop closure and fricative constriction are made at the nasopharyngeal port. 3. Combined with the nasal articulation, some cases have other disorders such as cleft palate, slight hearing loss, mental retardation and other types of functional articulation disorders. 4. Out of 37 cases, 13 showed spontaneous recovery and 15 cases were successfully corrected by the articulation training.