Tonsillar hypertrophy is common in young children and affects several aspects of the speech such as distortions of the dento-alveolar consonants. The study objective was to assess /s/-articulation, perceptually and acoustically, in children with tonsillar hypertrophy and compare effects of two types of surgery, total tonsillectomy and tonsillotomy. Sixty-seven children, aged 50-65 months, on the waiting list for surgery, were randomized to tonsillectomy or tonsillotomy. The speech material was collected preoperatively and 6 months postoperatively. Two groups of age-matched children were controls. /S/-articulation was affected acoustically with lower spectral peak locations and perceptually with less distinct /s/-production before surgery, in comparison to controls. After surgery /s/-articulation was normalized perceptually, but acoustic differences remained. No significant differences between surgical methods were found.