Abt monitored the resistance of Anopheles gambiae sensu lato (s.l.) to permethrin and deltamethrin before and after a mass distribution of long-lasting insecticidal nets (LLINs) in Kinshasa in December 2016 and in six other sites in the Democratic Republic of Congo in 2017 and 11 in 2018. We detected moderate or high intensity pyrethroid resistance nationwide, which is a serious threat to sustained malaria control with pyrethroid LLINs. PBO nets or bi-treated nets should be considered for mass distribution.