Three cases of serious eye infection (two endophthalmitis, one orbital cellulitis; two caused by Staphylococcus aureus, one caused by viridans streptococci) occurred shortly after surgery (two cataracts, one retinal detachment repair) within two weeks. There had been construction work adjacent to the theatres during this time, and fine dust was found on horizontal surfaces. Further surgery was cancelled, the construction work was completed and theatres were cleaned before recommencing with no further infections. Following a review of factors that may be involved in the pathogenesis of endophthalmitis, it is proposed that the mechanism of infection in these cases may have been due to the presence of foreign material enhancing the pathogenicity of the small numbers of organisms often found in intra-ocular fluids during surgery. This hypothesis could be tested in experimental models of endophthalmitis.