A sensitive and rapid method was developed for the determination of cAMP in Locusta migratoria manilensis Meyen by high-performance liquid chromatography with fluorescence detection. The cAMP was derivatized using chloroacetaldehyde and TBAS buffer/methanol was used as the mobile phase. A detection quantification of 40 fmol/ml could be achieved when using fluorescence detection. An HPLC-MS method using DMHA as an ion-pair agent to analyze cAMP was also demonstrated. We studied the effect of dopamine and other stimulants on cAMP levels from isolated locust central nervous systems. The new method is well suited for the analysis of cAMP in small biological samples.