Global lifetimes and concentrations of gaseous methylamines (MMA, DMA, and TMA) have been simulated. Oxidation and aerosol uptakes are dominant sinks for these methylamines. The oxidation alone leads to their lifetimes of 5-10h in most parts of low and middle latitude regions. The uptake by secondary species can shorten their lifetime to as low as 1-2h over central Europe, eastern Asia, and the eastern US. The modeled concentrations are substantially lower than observed values available.