AIM To explore the effects of trip-tolide on endothelin-1 and its gene expression in lung of asthmatic guinea-pigs. METHODS The contents of ET-1 in lung of asthmatic guinea-pigs were measured with radioimmunoassay, and the expressions of ET-1, ETA, ETB and ECEmRNA with reverse transcription DNA polymerase chain reaction (RT-PCR). RESULTS 0 All of the indexes were increased after guinea-pigs were induced asthma. At the 4th hour after first induction of asthma, ET-1 reached the top, but at the 2rd hour, ET-1mRNA, ETAmRNA and ECEmRNA were markedly higher than control group (P