Background Parents consistently report working memory deficits in children with sleep-disordered breathing (SDB); however, results from objective testing measures are inconsistent. This study aims to examine and compare working memory performance in children with various degrees of severity of SDB using both parent report and objective testing. Methods Subjects included 127 children aged 7–12years (mean age 9.6±1.6y: 71M/56F). Overnight polysomnography classified subjects into four groups: control (N =34); primary snoring (PS: N =55), mild obstructive sleep apnoea (mild OSA: N =22) and moderate to severe OSA (MS OSA: N =16). The Behaviour Rating Inventory of Executive Function (BRIEF) was used as the parent reported measure of working memory. A computerised task involving immediate recognition of playing cards (CogHealth) was used as the objective measure. Results Results of the BRIEF revealed working memory deficits at all severities of SDB compared to controls. Results of CogHealth revealed no difference between SDB groups and controls; however, mild OSA performed significantly worse than PS. Comparison of the two measures revealed that parents of controls reported less deficits, and parents of PS reported more deficits, than were found on the objective measure of working memory. Conclusions This study showed that parents of children with less severe SDB have a tendency to overestimate the level of working memory deficit in their children, possibly as a reflection of behaviour. This suggests that observation of deficits in working memory may be largely dependent on the assessment method and children with SDB may not be as impaired as previously thought.