Breast conservation therapy has gained acceptance as treatment for limited disease due to breast cancer. Unfortunately, a minority of patients who undergo this therapy will develop cellulitis of the breast, often recurrently, months to years later. A definitive pathogen has not been identified in the large majority of cases reported to date. Whilst some patients develop systemic toxicity with local skin changes of cellulitis, others manifest no fever, chills or leukocytosis. Local breast findings gradually clear with antibiotic treatment; when breast changes persist, non-inflammatory causes, including tumour recurrence, of the breast should be considered. More study is needed to define risk factors for the development of breast cellulitis complicating breast conservation therapy.