BACKGROUND: Hydrocele of the canal of Nuck is a rare pathology with a prevalence of approximately 1% in females aged 0-16 years. Its prevalence in adults remains unknown. The condition develops due to persistent patency or failed obliteration of the canal of Nuck. Several factors may contribute to its development, including lymphatic disorders, trauma, infection, inflammation, or idiopathic causes. Clinically, it presents as edema in the groin or genital region without additional symptoms. Ultrasonography is the preferred diagnostic modality for hydrocele of the canal of Nuck. CASE REPORT: We present the case of a 20-month-old female patient who presented with pain and a "lump" in the right inguinal region for 3 days. The patient was diagnosed with type 1 hydrocele of the canal of Nuck through ultrasonography, which was subsequently confirmed during surgery. The patient was discharged on the same day as the procedure and remains asymptomatic. CONCLUSIONS: Although rare, hydrocele of the canal of Nuck should be considered in the differential diagnosis of groin or genital region edema presenting without additional symptoms. Its diagnosis can be challenging due to several common differential diagnoses, including indirect inguinal hernia, tumors, cysts, abscesses, and lymphadenopathies, which occur more frequently. Therefore, ultrasonography plays a crucial role in evaluating these differential diagnoses and confirming the hydrocele of the canal of Nuck.