Mediastinal pancreatic pseudocyst is a rare occurrence in children and may be difficult to diagnose. Internal drainage via a cystenterostomy and a simple external drainage are two of the treatment options that are currently employed. We describe the case of an 11-year-old boy with a mediastinal pseudocyst who was treated via a thoracoscopic approach using an original pulmonary exclusion. The pseudocyst disappeared in 15 days and there has been no recurrence. No adjuvant treatment was necessary. Endoscopic retrograde cholangiopancreatography (ERCP) was useful in establishing the etiology (pancreas divisum). We believe that the thoracoscopic approach is a reproducible, simple, and safe procedure for the treatment of mediastinal pseudocysts. The technique may represent a valid alternative to cystogastrostomy.