In this paper, a study on the applicability of the HS-SPME method combined with GC–MS for pesticide determination in serum samples is reported. Development and optimization of SPME procedures were carried out separately for several pesticides by using GC-MS. Quantitation has been performed using calibration curves prepared by spiking blank blood samples, and using labelled surrogate standards. The developed multiresidue procedure will be applied to serum samples from patients.