We studied 1,629 febrile patients from a rural area of Malaysia, and made a laboratory diagnosis in 1,025 (62.9%) cases. Scrub typhus was the most frequent diagnosis (19.3% of all illnesses) followed by typhoid and paratyphoid (7.4%); flavivirus infection (7.0%); leptospirosis (6.8%); and malaria (6.2%). The hospital mortality was very low (0.5% of all febrile patients). The high prevalence of scrub typhus in oil palm laborers (46.8% of all febrile illnesses in that group) was confirmed. In rural Malaysia, therapy with chloramphenicol or a tetracycline would be appropriate for undiagnosed patients in whom malaria has been excluded. Failure to respond to tetracycline within 48 hours would usually suggest a diagnosis of typhoid, and indicate the need for a change in therapy.