Abstract Objective Obstructive Sleep Apnea (OSA) is associated with neuropsychological challenges, including attentional difficulties (Kim et al., 2017), and commonly comorbid with Posttraumatic Stress Disorder (PTSD) in veteran samples (Yesavage et al., 2014). We further explore the relationship between OSA and cognition in veterans with PTSD symptomatology. Method 58 veterans (6 females; mean age = 57.53 years, SD = 13.63) with OSA were screened as part of a larger outpatient study at Palo Alto VA Hospital, completing neuropsychological testing and Clinician Administered PTSD Scale for DSM-5 (CAPS-5) interview. Mean Apnea Hypopnea Index (AHI) was 23.95 (SD = 15.97). Positive Airway Pressure (PAP) therapy had not started at the time of screening. Domain-specific composite scores were created using z-score transformation of individual test scores and hierarchical regression used. Results Initial regression model was significant (F(1,57) = 4.99, p = 0.03, R2 = 0.081) with AHI significantly predicting executive function (EF; β = −0.28, p = 0.03). Attention was then entered into the model (F(2,56) = 22.31, p < 0.01, R2 = 0.44) and significantly predicted EF (β = 0.63, p < 0.01), but AHI was no longer significant. Lastly, CAPS-5 score (last month) was entered as a covariate to control for PTSD symptom severity (F(3,55) = 14.94, p < 0.01, R2 = 0.45); however, attention remained the only significant predictor of EF (β = 0.63, p < 0.01). Conclusions Findings suggest that EF concerns related to OSA may be driven by decreased attention performance, suggesting areas to highlight when formulating recommendations and treatment planning. Further implications and directions to be discussed. Funding Acknowledgements Supported by the Research Service of the Department of Veterans Affairs (Grant Number 1I01RX001799-01A2), VAPAHCS, and Sierra-Pacific MIRECC.