BACKGROUND: Conventional transbronchial needle aspiration (TBNA) is a cheap, minimally invasive tool for lung cancer staging and diagnosis. Endobronchial ultrasound-guided TBNA (EBUS-TBNA) is more sensitive but is more expensive and less widely available. We describe a prospective analysis of TBNA diagnostic, staging and cost utility in a centre in the UK. Objectives: To illustrate the potential diagnostic, staging and cost utility of a low cost conventional TBNA service. METHODS: A prospective analysis of 79 TBNA procedures over a 2-year period was performed looking at performance and cost utility in a 'mixed' cohort with variable pre-test probability of malignancy (year 1) followed by a high probability cohort (year 2). RESULTS: TBNA avoided mediastinoscopy in 25% of the cases overall (37% in high probability vs. 13% in the 'mixed' cohort, p = 0.03). The overall prevalence of malignancy was 84%, sensitivity 79%, negative predictive value 58% and accuracy 85%. Diagnostic utility varied with pre-test probability and nodal station. TBNA down-staged 8% of lung cancer patients to receive surgery and confirmed the pre-treatment stage (inoperability) in 74%. TBNA led to theoretical cost savings of GBP 560 per patient. CONCLUSIONS: TBNA can achieve a high diagnostic sensitivity for cancer in high probability patients and stage the majority appropriately, thereby avoiding unnecessary mediastinoscopies and reducing costs. It may also down-stage a minority to have surgery. TBNA is cheap, routinely available and learnable. As EBUS-TBNA will take time to develop due to its costs, all respiratory centres should perform TBNA at flexible bronchoscopy in suspected lung cancer with accessible mediastinal adenopathy.