Abstract Background Recent international guidance recommends the use of catheter-directed thrombolysis (CDT) in selected patients with symptomatic iliofemoral deep vein thrombosis (DVT). The aim of this study was to estimate the potential increase in workload as a result of this recommendation. Methods Using the radiology database, a review was performed of all DVTs diagnosed between August 2010 and February 2012 at a large tertiary referral hospital. The National Institute for Health and Clinical Excellence and American College of Chest Physicians guidance was applied retrospectively to this cohort, using case-note review by two independent clinicians to determine which patients would have been suitable for CDT. Results Some 563 patients had DVT confirmed radiologically over the 18-month interval. Fifty-three of the 128 patients with iliofemoral DVT would have been eligible for intervention with CDT, equivalent to 4·4 patients per 100 000 per year. Only eight (15 per cent) of the 53 were actually referred to vascular services for treatment. All eight patients had successful CDT, which involved a stay in critical care for monitoring (median 2 (range 1–3) sessions). Conclusion Vascular units should be prepared for a major increase in the requirement for CDT for iliofemoral DVT. This increase will affect inpatient beds, the interventional radiology suite, critical care and interhospital referrals.