Cultures were made from blood, bone marrow, stool and duodenal contents (obtained with string capsules) from 36 patients with bacteriologically proven typhoid fever on admission to hospital. Duodenal content cultures proved to be as sensitive in diagnosis (86%) as bone marrow (75%) and more effective than blood (42%) and stool (26%) cultures in recovery of Salmonella typhi The sensitivity of duodenal content cultures was not modified by the duration of illness at admission or by previous antibacterial therapy. Even on the seventh day of effective treatment with chloramphenicol, the culture of duodenal contents remained positive in 8 of 17 patients, whereas salmonellae were isolated from stool cultures in only 2 of the same patients. The results obtained with the string capsule, together with the simplicity, economy and acceptability of the procedure, the fact that it can be performed with minimal facilities and the advantages of bacteriological recovery for antibiotic sensitivity testing, suggest that its adoption would be very helpful in efforts to control this disease.