Although previous findings suggest that motor preparation can be initiated unconsciously, there is some debate as to whether inhibitory control can occur unconsciously. Results from research involving response conflict points to an association between inhibitory control and conscious awareness. However, no previous research has assessed whether unconscious information can influence brain activity correlates of inhibition when a response must be completely withheld. We recorded event-related potentials (ERPs) in a go/no-go task with subliminal primes and demonstrated that inhibition-related ERP components were modulated as a function of the congruency of the primes. Furthermore, these ERP modulations were directly related to the extent to which participants' performance was influenced by the primes. These findings suggest that inhibition of an impending motor action can be initiated by an unconscious stimulus.