A large open-heart surgery unit dealing with approximately 1000 elective patients per annum and housed in a dedicated suite, including a specialized intensive therapy unit, has provided a unique model for the study of predictors of infections and related phenomena. Over more than 10 years a series of studies has shown: the powerful effect of antibiotic usage on the colonization/infection rates with Gram-negative bacilli; the predictive relationships between preoperative chest status and the development of postoperative chest problems; an important correlation between preoperative peak urine flow rates and susceptibility to postoperative urinary tract infections; and the predictive significance of preoperative antibodies to enteric Gram-negative bacilli in relation to postoperative pyrexia and Gram-negative infection. The lessons learned from this easily studied group of patients may have important applications in other surgical settings.