1. An account is given of the finding of 19 symptomless excreters ofSalm. typhiand of 15 incubating cases (‘precocious carriers’) in the course of repeated examination of the faeces of 435 staff and patients at the hospital.2. In a comparison of the frequency of isolation ofSalm. typhifrom the faeces it was found that the the selenite F enrichment method was more efficient than enrichement in Kauffmann 's tetrathionate broth, and that both methods were superior to direct plating on desoxycholate citrate agar.3. Examination of sera from cases of typhoid fever showed that, in some cases, H- and O-agglutinin titres which would normally be regarded as ‘diagnostic’ may be reached well within the first week of illness.4. Measures are described which were taken to exclude connexion between this outbreak and (a) a chronic carrier found during investigation of the hospital milk supply, and (b) the incidence of typhoid fever at another hospital.5. A case of typhoid fever at Shrewsbury is described which was probably infected by an abortive missed case. Attempts to make a retrospective bacteriological or serological diagnosis of the latter were unsuccessful.6. An account is given of the use of the sewage-pad method in an attempt to trace the source of infection in the case of a sewer worker who developed typhoid fever 14 months after the main epidemic and was probably infected by an intermittent carrier at the hospital.