This phase III, open-label, multi-centre study investigated the efficacy, safety, pharmacokinetics and quality of life impact of Evogam(®), a new chromatographically fractionated 16% subcutaneous immunoglobulin, utilising a 1:1 dose transition ratio from previous immunoglobulin therapy. Thirty-five previously treated patients with primary immunodeficiency received weekly Evogam over 36 weeks. Primary endpoints were rate of serious bacterial infections (SBIs) and steady-state serum immunoglobulin G (IgG) trough concentrations. No SBIs were reported during the study. Evogam produced significantly higher mean trough IgG concentrations with 1:1 dose conversion compared to previous immunoglobulin treatment (8.94 versus 8.27 g/L, p = 0.0063). Evogam was efficacious in the prevention of infections and maintenance of trough levels using a 1:1 dose conversion. It was well tolerated with no withdrawals due to adverse events and was preferred to IVIg by the majority of patients.