The number of children with autism is increasing worldwide. These children like all other children should be provided with equal chances for learning and education. Thus, English language education is not an exception as the need to learn it in today's world is inevitable. The present study sought to investigate the effect of employing Picture Exchange Communication System (PECS) on English as a foreign language vocabulary learning relying on its effectiveness in first language communication. As a single-subject study an experimental A-B design was employed through repeated measurement. The participants were two high-functioning children with autism aged 9 and 12 at a school for students with special needs. The treatment phase included 15 sessions. An analysis of visual inspection and graphic representation revealed performance improvement in both cases after the intervention. Moreover, some problems while educating the two participants for English vocabulary including lack of cooperation in phase 2, lack of attention and cooperation in mid-intervention, sense problems such as proprioceptive and vestibular are reported through qualitative analysis of the reports made of weekly sessions.