Endoscopic-assisted approaches have been shown to be a suitable alternative to the standard microscopic approach to pineal region tumours. With extension laterally into the ventricles, the 0° endoscope and microscope have significant limitations. We describe the extended endoscopic supracerebellar infratentorial (EESI) approach using angled endoscopes for a complex pineal region tumour that extended into the lateral ventricle. A 15-year-old boy presented with headaches and ataxia. MRI revealed a pineal region tumour extending into the lateral ventricle. The patient was positioned in the sitting position. The supracerebellar infratentorial corridor was accessed through a small craniotomy. The tumour was resected completely via the endoscope. Postoperatively, the patient's symptoms resolved completely. We believe that this case highlights the benefit of using the endoscopic extended supracerebellar infratentorial (EESI) approach to resect pineal region lesions that extend beyond the midline.