Bed bugs,Cimex lectulariusandC. hemipterus,are common blood-sucking ectoparasites ofhumans with a large geographical distribution, worldwide. In France, little is known about the statusof bed bugs’ infestation and their resistance to insecticides, particularly, pyrethroids. Here, we aimed to find mutations in thekdrgene, known to be involved in resistance to insecticides. We gatheredbed bugs from various infested locations, including 17 private houses, 12 HLM building complex,29 apartments, 2 EHPAD, and 2 immigrants’ residences. A total of 1211 bed bugs were collected andmorphologically identified asC. lectularius. Two fragments of thekdrgene, encompassing codonsV419L and L925I, were successfully amplified for 156 specimens. We recorded sense mutation inthe first amplified fragment (kdr1) in 89 out of 156 (57%) samples, in which in 61 out of 89 (68.5%)sequences, a change of valine (V) into leucine (L) V419L was observed. Within the second fragment(kdr2), a homozygous mutation was recorded in 73 out of 156 (46.7%) specimens at the codon 925.At this position, 43 out of 73 (58.9%) specimens had a sense mutation leading to the replacement ofleucine (L) by isoleucine (I). Among 162 mutant sequences analyzed (89 for thekdr1fragment and 73for thekdr2one), we detected single point mutation in 26.6%, while 73.4% presented the mutationin bothkdr1andkdr2fragments. All modifications recorded in bed bug populations of Paris aredescribed to be involved in the knockdown resistance (kdr) against pyrethroids.