The objective of this study was to evaluate the usefulness of electropalatography (EPG) as a method for diagnostic analysis of the [s] sound and also to make a multiple analysis of the production of the normal Swedish [s]sound in various contexts. Eleven dental students participated. EPG registration, optoelectronic recording of jaw movements, and acoustic registration of a test phrase were made simultaneously. A speech perceptual test was also made. There were four separate recording sessions. Except for at session I, subjects wore an EPG palate. At Session II they were not adapted to it, in contrast to the later occasions. The EPG appeared to be a valid method for investigating the [s] sound. In general, EPG and mandibular movement patterns were similar between sessions, and the sound quality normal throughout. At session II, however, the tongue groove was wider, the mandibular movements smaller, and the [s]quality somewhat deteriorated, [s] in various contexts had different tongue groove widths but similar high average mandibular position. To prevent speech and especially [s]sound problems when constructing prosthetic devices, it is important to advance our knowledge of [s] sound production.