The purpose of this study was to examine the effectiveness of self-monitoring on on-task behaviors and percent of correct response of children with autism spectrum disorders. The study group consisted of three children with autism who were aged 10 to 11 and who attended a special education rehabilitation center in Ankara. A multiple probe design with probes across subjects was applied as research design. The results showed that self-monitoring increased on-task behaviors of three subjects and it also considerably increased academic achievement related to addition skills of two subjects. Moreover the findings exhibited that the subjects maintained their achievements on on-task behaviors and percent of correct response after two, four, and six weeks after the intervention was terminated and they also transferred their skills to group settings. Social validity of this study was conducted by teacher interviews and teachers indicated that self-monitoring was effective and easy to implement. The results of this study are discussed in line with the current literature and suggestions for practice are included.