['Hilar cholangiocarcinoma presents both diagnostic and therapeutic challenges. While establishing a diagnosis is important for patients considering aggressive treatment, a transperitoneal fine needle aspiration (FNA) may lead to seeding of the tumour. The aim of the present study was to determine whether patients who have undergone transperitoneal FNA of the primary tumour have a higher incidence of metastases.', 'Outcomes of 191 patients enrolled in a neoadjuvant chemoradiotherapy followed by liver transplantation (LT) from 1 October 1992 to 1 January 2010 were analysed. The incidence of metastases was compared between those who did or did not undergo a transperitoneal FNA biopsy of the primary tumour.', 'A total of 16 patients underwent FNA biopsy. There were six patients with biopsies positive for adenocarcinoma and 5/6 (83%) had peritoneal metastases at operative staging. Nine patients had biopsies, which did not demonstrate a tumour, and had no evidence of metastasis. One patient had an equivocal biopsy. Of those who did not undergo a transperitoneal biopsy, the incidence of peritoneal metastasis was 8% (14/175), P= 0.0097 vs. positive staging (83%) in those with a diagnostic transperitoneal FNA. Survival at 5 years for those who underwent LT was 74%.'] Is trans-peritoneal fine needle aspiration biopsy of hilar cholangiocarcinoma associated with disease dissemination?