Purpose <p>Adenomyosis is a chronic uterine disorder characterised by ectopic endometrial tissue within the myometrium, frequently associated with dysmenorrhea, abnormal uterine bleeding (AUB), chronic pelvic pain (CPP), and dyspareunia. No standardised guidelines are currently available for its management, and therapeutic options remain limited for women seeking fertility preservation. This study aimed to evaluate the efficacy of intravaginal progesterone in alleviating adenomyosis-related symptoms in patients seeking fertility preservation.</p> Methods <p>In this prospective monocentric observational study, 85 patients aged 22–50&#xa0;years with ultrasound-confirmed symptomatic adenomyosis were enrolled between April 2020 and April 2024. Inclusion criteria were age 18–55&#xa0;years, BMI 18–35, and a Visual Analogue Scale (VAS) score ≥ 7 for dysmenorrhea, AUB, CPP, or dyspareunia. All patients received 200&#xa0;mg/day of intravaginal progesterone for 10&#xa0;days per cycle. Symptom severity was assessed using VAS scores at baseline and at 6&#xa0;months. Data were analysed using non-parametric statistical tests.</p> Results <p>Sixty-five patients completed the 6-month follow-up. Four patients conceived during treatment and were excluded from the final analysis. Statistically significant improvements were observed for all assessed symptoms (all p &lt; 0.05). Median VAS scores decreased for dysmenorrhea (9 to 6, p &lt; 0.001), AUB (8 to 6, p &lt; 0.001), chronic pelvic pain (5.5 to 3.5, p &lt; 0.001), and dyspareunia (2 to 0, p = 0.020). The overall treatment satisfaction was high, with a mean Likert score of 7.5 out of 10.</p> Conclusion <p>Intravaginal progesterone appears to be an effective fertility-sparing treatment for symptomatic adenomyosis, providing significant relief across all primary symptoms, with high patient satisfaction. Larger controlled studies are warranted to confirm these preliminary findings and further define its role in clinical practice.</p>