Background: Poor adherence to iron chelation may underlie the detrimental levels of iron overload previously reported among transfusion-dependent thalassaemia (TDT) patients in Sri Lanka. Given the many challenges faced by these patients and families, psychosocial factors may have a significant impact on medication adherence. Objective: To assess chelation adherence among TDT patients and explore associated psychosocial factors. Method: TDT patients, aged over 4 years, admitted for blood transfusion to a tertiary care hospital, as well as their mothers, were recruited. Medication adherence was assessed using a questionnaire adapted from Brief Adherence Rating Scale. Serum ferritin (SF) values were recorded as objective measures of non-adherence. Mental health status of patients and their mothers was assessed using Strengths and Difficulties Questionnaire (SDQ) and General Health Questionnaire-30 (GHQ) respectively. Associated psychosocial factors were analysed using multiple linear regression. Results: Fifty two patients aged 4 to 28 years participated. Thirty four (65%) were female. The average adherence rate was 90%. One fifth of patients had an adherence percentage less than 80%. The mean ferritin level was 3260 ng/ml, whereas 46.2% of patients had SF levels exceeding 2500ng/ml. SF levels correlated positively with non-adherence (r=0.34, 95%CI: 0.071-0.606, p=0.014). Based on multivariate analysis, _________________________________________