We performed a randomized controlled trial involving 55 adult patients with enteric fever to compare ciprofloxacin and chloramphenicol. Blood and bone marrow cultures and cytokine profiles during therapy were done to compare the clinical and bacteriological efficacies of these drugs. All patients were randomly assigned to receive chloramphenicol (500 mg four times a day orally) for 14 days or ciprofloxacin (500 mg twice a day orally) for 7 days. In each treatment group, patients were subsequently randomized to have blood and bone marrow cultured after either 3 or 5 days of treatment. Twenty-seven patients received chloramphenicol, and 28 received ciprofloxacin. The two groups were similar in terms of baseline characteristics. No significant differences in clinical cure and time to defervescence were found. All strains isolated were susceptible to both antibiotics. Although ciprofloxacin was more effective in the elimination of Salmonella enterica serovars Typhi and Paratyphi A from bone marrow than chloramphenicol, there was still an impressive persistence of Salmonella in the bone marrow culture (67%). In the ciprofloxacin-treated patients the suppressed cytokine production capacity showed a trend to normalize earlier than in patients treated with chloramphenicol.