Extracorporeal photopheresis (ECP) has become a recognised treatment for steroid-refractory chronic GVHD (cGVHD), but the optimal frequency and duration of treatment are yet to be established. We report on 82 consecutive patients with mucocutaneous cGVHD who received a bimonthly regimen of ECP treatment for two consecutive days, which could be subsequently tapered to a monthly regimen depending on response. Patients were steroid-refractory, steroid-dependent or steroid-intolerant, and 29 (35%) had multiorgan involvement. The median duration of treatment was 330 days (42-987). The median number of ECP cycles was 15 (1.5-32). Response was assessed by clinical assessment and reduction in immunosuppression after 6 months. 69/82 (84%) had completed 6 months of ECP and 65/69 (94%) had ≥ 50% improvement in symptoms and signs of cGVHD. A total of 77% of patients who completed 6 months of ECP had a reduction in immunosuppression dose and 80% had decreased their steroid dose (27.5% stopped, 30% had ≥ 75% reduction, 17.5% had ≥ 50% reduction and 25% had <50% reduction). OS at 3 years from the start of ECP was 69%. This study reports the largest series of patients receiving bimonthly ECP treatment for cGVHD, and confirms that ECP allows successful reduction of immunosuppression.