Tension-type headache (TTH) development is linked to the presence of myofascial trigger points (TrPs) and muscular tenderness. These TrPs, when in an active state within the muscles of the head and neck, can manifest as referred pain that is perceived in the head. Objective: The current study was conducted to investigate the effect of magnesium sulphate (MgSO4) iontophoresis on suboccipital TrPs in TTH patients. Methods: This study was conducted on forty patients (30 females and 10 males) with a clinical diagnosis of TTH and active myofascial TrPs on the occipital muscles bilaterally. The participants' ages varied between 30 and 45 years. They were randomly divided into two groups of equal size: the study group (GA) and the control group (GB). Group A (study group) underwent MgSO4 iontophoresis on the occipital muscles along with conventional physical therapy biweekly for four weeks. Group B (control group) underwent a placebo iontophoresis (without medication) along with conventional physical therapy biweekly for four weeks. Each patient in both groups was evaluated by visual analogue scale(VAS) to assess pain, Digital Electronic Pressure Algometer to assess pressure pain threshold(PPT)and headache disability index(HDI)to assess the headache impact on daily living before and after a four-week treatment period. Results: The present study demonstrated a statistically significant reduction in the mean scores of VAS and HDI, alongside a significant increase in the mean scores of PPT in the study group in comparison to the control group after treatment. Conclusion: Magnesium sulfate iontophoresis has a significant effect in improvement of VAS, PPT, and HDI in patients suffering from TTH due to suboccipital TrPs.