Methods Forty-one subjects who have MPS in the upper trapezius muscles without depression were recruited. The patients were randomly assigned into two groups: the whirlpool therapy group whose bodies were immersed in a whirlpool bath at 34oC—36oC for 30 minutes; the hydrocollator group who took a 30-minute application of a standard hot hydrocollator pack. Patients in both groups received therapy three days a week for 2 weeks and underwent several evaluations at baseline and after treatment. The variables we analyzed during evaluations were as follows: the primary outcome we considered was pain severity using a visual analogue scale. And the secondary outcomes examined included anxiety using the Korean version of the Beck Anxiety Inventory and quality of life (QoL) using the Korean version of the World Health Organization QoL Assessment, Brief Form. All follow-up values were compared with the baseline values.