The effects of linear vestibular stimulation on body-rocking behaviors in adults with profound mental retardation were studied. A single-system multiple baseline design across 3 subjects was used. The design included three phases spread over a period of 9 weeks. An interval time sampling procedure was used to collect data. Data from the 3 subjects were graphed and interpreted through visual inspection. Trend lines were computed with the celeration line approach to supplement the visual inspection of the data. The results demonstrated a decrease in body-rocking behaviors during the treatment and follow-up phases for Subject 2 but no obvious change in performance for Subjects 1 and 3. A lengthier treatment period and selection of subjects with similar body-rocking frequencies are suggested for further research.