Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are related inflammatory rheumatic conditions affecting adults over the age of 50 years. Both conditions respond to initial glucocorticoid (GC) therapy. However, most patients require 12–36 months of a tapering steroid regime. Adverse events at 2 years are seen in up to 65% of patients with PMR and 86% of patients with GCA with over 50% developing serious events. There is also a high incidence of relapse in both diseases −40% within 2 years for GCA and 50% of patients with PMR at some point having a relapse. Effective steroid-sparing adjuvant therapies are urgently required especially in incomplete, poorly sustained or non-responders to glucocorticoids. In this case series, we found that Leflunomide is efficacious, with 22 out of our 23 patients exhibiting a complete or partial response. It was also steroid sparing and well tolerated. It may be a useful adjunctive agent in difficult-to-treat GCA and PMR. Prospective randomised controlled trials of Leflunomide in both GCA and PMR are now required.