Four hundred and thirty-eight overtly healthy adults on Tiree were screened for bacteriuria by dip-inoculum culture and a tetrazolium reductase test.Dip-inoculum culture affords a simple and effective means of providing a service in quantitative urine bacteriology for communities remote from a laboratory.The pattern of bacteriuria on Tiree is much the same as in other communities surveyed. Criteria are discussed for assessing the sensitivity of the tetrazolium test in terms of quantitative urine culture.