OBJECTIVE: This study aimed to assess the effects of single and multiple massage treatments on pressure-pain threshold (PPT) at myofascial trigger points (MTrPs) in people with myofascial pain syndrome expressed as tension-type headache. DESIGN: Individuals (n = 62) with episodic or chronic tension-type headache were randomized to receive 12 twice-weekly 45-min massage or sham ultrasound sessions or wait-list control. Massage focused on trigger point release (ischemic compression) of MTrPs in the bilateral upper trapezius and suboccipital muscles. PPT was measured at MTrPs with a pressure algometer pre and post the first and final (12th) treatments. RESULTS: PPT increased across the study timeframe in all four muscle sites tested for massage, but not sham ultrasound or wait-list groups (P < 0.0001 for suboccipital; P < 0.004 for upper trapezius). Post hoc analysis within the massage group showed (1) an initial, immediate increase in PPT (all P values < 0.05), (2) a cumulative and sustained increase in PPT over baseline (all P values < 0.05), and (3) an additional immediate increase in PPT at the final (12th) massage treatment (all P values < 0.05, except upper trapezius left, P = 0.17). CONCLUSIONS: Single and multiple massage applications increase PPT at MTrPs. The pain threshold of MTrPs have a great capacity to increase; even after multiple massage treatments additional gain in PPT was observed. TO CLAIM CME CREDITS: Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Understand the contribution of myofascial trigger points to myofascial pain; (2) Describe an effective treatment for decreasing tenderness of a myofascial trigger point; and (3) Discuss the relative values of single vs. multiple massage sessions on increasing pressure-pain thresholds at myofascial trigger points. LEVEL: Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 0.5 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.