Cymbopogon citratus is one of the most used plants in Brazilian folk medicine for the treatment of nervous and gastrointestinal disturbances. It is also used in many other places to treat feverish conditions. The usual way to use it is by ingesting an infusion made by pouring boiling water on fresh or dried leaves (which is called "abafado" in Portuguese). Abafados obtained from lemongrass harvested in three different areas of Brazil (Ceará, Minas Gerais and São Paulo States) were tested on rats and mice in an attempt to add experimental confirmation to its popular medicinal use. Citral, the main constituent of the essential oil in Brazilian lemongrass, was also studied for comparison. Oral doses of abafados up to 40 times (C40) larger than the corresponding dosage taken by humans, or of 200 mg/kg of citral, were unable to decrease body temperature of normal rats and/or rats made hyperthermic by previous administration of pyrogen. However, both compounds acted when injected by intraperitoneal route. Oral administration of doses C20 -C100 of abafados and 200 mg/kg of citral did not change the intestinal transit of a charcoal meal in mice, nor did it decrease the defecation scores of rats in an open-field arena. Again, by intraperitoneal route both compounds were active. The possible central nervous system depressant effect of the abafados was investigated by using batteries of 12 tests designed to detect general depressant, hypnotic, neuroleptic, anticonvulsant and anxiolytic effects. In all the tests employed, oral doses of abafados up to C208 or of citral up to 200 mg/kg were without effect. Only in a few instances did intraperitoneal doses demonstrate effects. These data do no lend support to the popular oral therapeutic use of lemongrass to treat nervous and intestinal ailments and feverish conditions.