An assay of phosmet residues in human blood by gas chromatography coupled to mass spectrometry (GC/MS) Clarus® 600/560 DMS PerkinElmer® was developed and validated in human blood samples loaded by residues of this insecticide. The extraction of phosmet has been carried out in solid phase through C18 SPE cartridges. The proposed method of phosmet residue analysis by GC/MS uses a capillary type Supelco®, the oven temperature was programmed from 75°C to 320°C. The Helium was used as carrier gas with a flow rate of 0.8 ml / min. The Phosalone was used as internal standard (IS). The retention time of the analyte and EI are 14.34 and 14.67 ± 0.02 min, respectively. The calibration curve is linear in the concentration range between 10 and 100ppb with R2 = 0.998. The method was validated according to ICH guidelines Q2 (R1) in terms of the criteria of accuracy, precision, linearity and specificity. The validated method is selective and has a quantification limit of 10 ppb. It can be used routinely for the determination of phosmet residues in real samples of human blood.