We compared the use of right infra-axillary minithoracotomy and conventional median sternotomy in direct open-heart surgery in 59 adults undergoing elective surgery for mitral valve stenosis, mitral valve disease, atrial septal defect repair, left atrial myxoma excision or mitral and tricuspid valve disease. Patients were randomized to the infra-axillary minithoracotomy group (Group A; n = 29) or the median sternotomy group (Group B; n = 30). Post-operative outcomes (post-operative bleeding; cross-clamp time; length of hospital and intensive care unit stays; and postoperative blood transfusion and analgesic requirements) were recorded and compared; they were found to be significantly lower in Group A than Group B. We concluded that right infra-axillary minithoracotomy is less invasive and can be used safely in adults as an alternative approach to conventional median sternotomy for some cardiac operations. Further multicentre studies in adults are now needed.