Background: Rett syndrome (RS) is a pervasive developmental disorder with cognitive and neuromotor impairments (including loss of handiness and loss of communicative skills). Objective: To verify whether girls with RS use their gaze intentionally, by observing their performance in three cognitive tasks: (1) verbal instruction condition (look at picture X), (2) recognition and matching of pictures (look at the one that is the same), and (3) categorization of pictures (look at the one that is similar). Method: Seven girls diagnosed with RS according to DSM-IV criteria were studied. Eyegaze[R] technology was used to record the girls' eye movements' responses to visual stimulation. Results: The comparison of fixation time on the alternatives revealed a higher percentage (62.4%) of correct alternatives (X[squared]=76.31; P=0.000). Of the seven children assessed, only one did not present predominance of fixations on the correct alternatives in any one of the tasks. One did well in all tasks. Six responded correctly to all verbal instructions. Conclusion: The rate of correct answers suggests that there is measurable and intentional gaze in RS girls and it can be used as a path to explore their cognitive performance.