Infant immunisation is the most commonly performed health procedure in developed countries. Associated pain may be harmful because we do not know what painful experiences the infant has already had and whether it might contribute to a cumulative pain experience. Healthy infants undergo immunisation with minimal pain relief. However, immunisation pain can be managed using oral sweet solutions.To determine the effectiveness of 25% oral glucose solution in reducing immunisation pain in 2-month old infants.A double-blind, randomised controlled trial conducted in Jordan. A total of 120 healthy full-term infants who met the eligibility criteria and were attending immunisation clinics for routine 2-month immunisation were randomised to receive either 2mL of 25% oral glucose solution immediately prior to their immunisation or 2mL of oral sterile water. Researchers, nurses and parents were blind to the solution. Primary outcome was behavioural pain measured using the Modified Behavioural Pain Scale (MBPS). Secondary outcomes were crying time and duration of full-lung cry. Crying was registered from onset of the immunisation injection and for up to 120s after completion of the injection procedure.Infants in the intervention group experienced statistically and clinically significant reduction in behavioural pain responses (p<0.001), and spent less time crying up to 2min after the procedure (mean difference 38 vs. 77.9s).A 2mL oral dose of 25% glucose given immediately before an immunisation procedure reduces pain in 2-month old infants.