Hepatitis B virus (HBV) presents a risk to patients and staff in renal units. To minimise viral transmission, there are international and UK guidelines recommending HBV immunisation for patients commencing renal replacement therapy (RRT) and HBV surveillance in kidney transplant recipients. We report the case of a 56-year-old male who was immunised against HBV before starting haemodialysis. He received a deceased donor kidney transplant three years later, at which time there was no evidence of HBV infection. After a further six years he developed an acute kidney injury; allograft biopsy revealed an acute thrombotic microangiopathy (TMA) with glomerulitis, peritubular capillaritis, and C4d staining. Due to a "full house" immunoprofile, tests including virological screening were undertaken, which revealed acute HBV infection. Entecavir treatment resulted in an improvement in viral load and kidney function. HBV genotyping demonstrated a vaccine escape mutant, suggesting "past resolved" infection that reactivated with immunosuppression, though posttransplant acquisition cannot be excluded. This is the first reported case of acute HBV infection associated with immune complex mediated glomerulonephritis and TMA. Furthermore, it highlights the importance of HBV surveillance in kidney transplant recipients, which although addressed by UK guidelines is not currently practiced in all UK units.