Where lymphatic filariasis has diminished since about the 1950s, it has most frequently, though not always, been a direct result of chemotherapeutic intervention against the parasite. Diethylcarbamazine (DEC), a well-established drug, has been the single agent of chemotherapeutic control and has been successful in a wide variety of regimens. This paper reviews the experience with one strategy: long-term, low-dose treatment through DEC-medicated common salt. Diethylcarbamazine-medicated salt played a major role in the Chinese filariasis control program and has been successful in more limited trials in India, Brazil, and Tanzania. It is not being used today in any endemic area, but the evidence suggests that it is safe, effective, and relatively inexpensive. Enough is already known about the beneficial effects of DEC-medicated salt from community-wide studies to develop specific guidelines for its use in community programs.