To assess the role of clinical features in diagnosing seizures in children with autism spectrum disorder who present with staring spells. A 10-year retrospective chart analysis of autism spectrum disorder patients aged 3-14 years was performed at a tertiary care children's hospital. Patient demographics, clinical presentation, and epileptic seizure versus non-epileptic spell diagnosis were assessed. Target episodes of staring spells were captured during a long-term electroencephalogram monitoring record. Multilevel likelihood ratios and a receiver operating characteristic curve were determined using 8 of the 11 clinical variables. Among the cohort of 140 patients with autism spectrum disorder, 16% were diagnosed with epileptic seizures with the most common seizure being atypical absence seizures (64%). Clinical semiology differed between those diagnosed with epileptic seizures versus those diagnosed with non-epileptic spells in the average duration of episodes (42 s vs 87 s), frequency of spells per week (6 vs 11.5 spells), increase in frequency of staring spells over time (100% vs 40%), and response to verbal stimulation (0% vs 100%), respectively. Multilevel likelihood ratios based on the receiver operating characteristic curves and clinical semiology features may be helpful in differentiating epileptic seizures from non-epileptic spells in children with autism spectrum disorder.