Treatment of haematological disorders in patients with chronic hepatitis B or resolved infection (anti-HBc-positive) is associated with a risk of hepatitis B reactivation. Moreover, patients with chronic hepatitis C have a higher risk of haematological malignancies than general population. An electronic alert system was developed to promote screening of hepatitis B (HBV) and C (HCV) in patients starting haematological therapies. The system included screening and linkage to care and a request for testing in those without data. From March, 2017 to March, 2018 data from 420 consecutive patients with haematological diseases were included. At first prescription before the alerts, the HCV and HBV screening rate was 60.5%. Following the alerts, an additional 115 were screened, increasing the overall screening rate to 87.9%. Anti-HBc alone was detected in 57, anti-HCV in 13, and HBsAg in 2 patients. Overall, 68% of patients with any viral hepatitis markers were previously not know, and the impact was particularly important for anti-HBc detection (47/57 unknown). Nucleoside analogues were prescribed in 28 (49.1%) anti-HBc-positive and the 2 HBsAg-positive patients. Prospective follow-up with HBV DNA and HBsAg testing showed no cases of HBV reactivation. An estimated 1.2 HBV reactivations were avoided as consequence of the alert system. In summary, an electronic alert system increased viral hepatitis screening in patients receiving haematological treatment and led to improvements in the management of these patients, including avoided HBV reactivation.