Abstract: OBJECTIVE To establish a GC-MS direct injection method for the microdetermination of N-nitrosodimethylamine(NDMA) and N-nitrosodiethylamine(NDEA) in candesartan cilexetil. METHODS The GC-MS was used, and the separation was performed on a Agilent VF-WAX ms column(30 m×0.25 mm, 0.25 μm) with temperature programmed. The inlet temperature was 200℃ and the flow rate was 1.0 mL·min^-1. Mass spectrometry was used with EI source, the voltage was 70 eV, ion source temperature was 230℃ and quadrupole temperature was 150℃. The ion of 74(m/z) was detected for NDMA from 5 to 7 min, and the ion of 102(m/z) was detected for NDEA from 7 to 10 min. The samples were dissolved in 0.2 mol·L^-1 sodium hydroxide solution and extracted with ethyl acetate. RESULTS The separation between NDMA, NDEA and adjacent chromatographic peaks was effective. NDMA and NDEA revealed good linearities within the range of 2.97-148.5 ng×mL^-1 and 3.00-150.20 ng×mL^-1, respectively. The limit of quantitation of NDMA and NDEA were 0.06, 0.03 mg×g^-1 and the limit of detection were 0.018, 0.009 mg×g^-1, respectively. The average recoveries of NDMA were 86.3%, 88.3%, 91.4% at low, middle and high concentration, with the RSDs(n=3) of 0.9%, 0.7%, 0.4%, respectively. The average recoveries of NDEA were 88.1%, 87.9%, 91.7% at low, middle and high concentration, with the RSDs(n=3) of 0.9%, 1.1%, 0.2%. CONCLUSION The established GC-MS method for determination of NDMA and NDEA is accurate, highly sensitive, simple and reliable with less pollution to the instrument, and it can be used for the quality control of these two genotoxic impurities in candesartan cilexetil.