In this study the authors aimed to detect immune response to ranibizumab treatment in wet age-related macular degeneration (AMD). An ELISA was employed to quantify the anti-ranibizumab titre which was compared against the control anti-abciximab titre. Titres of anti-ranibizumab antibodies against the variable regions higher than 1:80 and at least four times higher than the control were considered positive. Anti-ranibizumab IgGs were detected in 17.1% of treated patients. No immunoreactivity was noted in the untreated (naïve) patients. For patients with 10 or fewer previous intravitreal injections (IVTs), immunisation against ranibizumab was detected in 11.1% whereas immunisation was observed in 21.7% with more IVTs (p=0.20). No record of uveitis was found in any of the patients included in the study. Factors evoking the immune response are unclear. Subconjunctival reflux may be responsible and patient related factors cannot be excluded. No attempt was made in this study to compare different patient profiles and the time interval between injections was not recorded. Immunity and drug resistance may be one of the key elements prevalent in AMD non-responders of intravitreal ranibizumab therapy, and merits further research.