Mycoplasma hominis is a rare cause of bacteraemia in adult males. We believe this report to be the first of Mycoplasma hominis bacteraemia and wound infection complicating cardiac surgery. Because of difficulties in isolating the organism, cases may be missed. Review of the literature on M. hominis bacteraemia in adult males reveals that infection is often mild and most often associated with urethral catheterisation. M. hominis is resistant to many antibiotics including erythromycin. If treatment is indicated, tetracycline or clindamycin is the drug of choice.