Background: Fibromyalgia (FM) is a syndrome of persistent widespread pain, stiffness, fatigue, disrupted and unrefreshing sleep, and cognitive difficulties, often accompanied by multiple other unexplained symptoms, anxiety and/or depression, and functional impairment of activities of daily living Objectives: To assess the frequency and pattern of enthesopathy in primary FM using musculoskeletal ultrasound with Glasgow Ultrasound Enthesitis Scoring System (GUESS) and Correlate these findings with clinical and laboratory parameters of FM. Patients and Methods: A cross-sectional study includes 100 persons divided into two groups as follows: Group (1): 50 patients with primary fibromyalgia syndrome (FM) were diagnosed. Group (2): 50 apparently healthy controls with comparable age and sex. Patients were selected from those attending the outpatient clinic of the Rheumatology & Rehabilitation Department of Al-Azhar University Hospital, Assiut. Results: There is no statistically significant difference between cases and control groups regarding age, gender, and BMI (P>0.05 for each), there were no statistically significant correlations between the GUESS scores and any of the clinical characteristics of FM patients. Although non-significant, these correlations were negative between the GUESS score and the tender point number, the Widespread Pain Index as well as the Fibromyalgia Impact Questionnaire. The total GUESS score of the FM group ranged between 0-12 with a mean ±SD of 5.3 ± 2.8. The total GUESS score of control group ranged between 0-6 with a mean ±SD of 0.97± 1.58, with a significant difference between the two groups (P<0.05) Conclusion: There were significant enthesopathic changes detected among FM patients especially affecting the Achilles, quadriceps, and proximal patellar tendons.