BACKGROUND Cardiac assessment was not done routinely in Duchenne (DMD) and Becker muscular dystrophy (BMD) patients in Northern region of England while evidence was gathering on progressive cardiomyopathy in these patients. We wanted to find out the prevalence, progression and clinical features of cardiac involvement in Duchenne and Becker muscular dystrophy. METHODS It is a retrospective review of clinical, electrocardiographic and echocardiographic assessments. RESULTS The notes of 52 Duchenne and Becker muscular dystrophy patients were reviewed out of which 32 had DMD, 6 had Intermediate muscular dystrophy (IMD) and 14 had BMD. Prevalence of preclinical and clinically evident cardiac involvement was 88.4% in DMD and BMD patients. Sixty nine% of patients had clinically evident cardiac involvement but only four patients had cardiac symptoms in the form of palpitations, out of which two were due to respiratory dysfunction and others was due to cardiac failure. Clinical examination of the rest of all of the patients was unremarkable. Electrocardiogram was abnormal in 88.4% of patients. Conduction defects were found in 19.4% of patients. Echocardiogram was abnormal in 80.7% of patients but all were poor echo subjects including those who had normal echocardiogram. CONCLUSIONS Though most patients were asymptomatic, a high percentage had evidence of preclinical and clinically evident cardiac involvement. So in all patients with Xp21 linked muscular dystrophy a routine baseline cardiac assessment should be done at the age of 10 years and reviewed after intervals of one to two years.