Objective To observe the diagnostic value of the modified National Institutes of Health Stroke Scale (mNIHSS) in evaluating sedation‑related focal neurological deficits for patients with supratentorial mass lesions. Methods Mild sedation related focal neurological deficits in patients with supratentorial mass lesions who were evaluated by National Institutes of Health Stroke Scale (NIHSS) were retrospectively enrolled. Both sedative‑induced positive change (NIHSS score change≥2) and negative change (NIHSS score change<2) patients were re‑evaluated by mNIHSS, and their diagnostic values were evaluated based on the results of NIHSS in the same population. Results NIHSS evaluation showed that after sedation, the neurological function scores of limb motor and limb ataxia were significantly increased after propofol and midazolam, and the limb motor scores were significantly increased after fentanyl and dexmedetomidine, with statistical significance (P<0.05). All NIHSS negative change patients were negative when evaluated by mNIHSS. For those having NIHSS positive changes, 51 out of 54 patients presented positive changes in mNIHSS evaluation and 3 out of 54 patients presented negative changes in mNIHSS. For supratentorial mass lesion patients, the sensitivity of mNIHSS tested sedative‑induced neurological deficits was 94.44%, the specificity was 100%，the rate of missed diagnosis was 5.56% and the misdiagnosis rate was 0. The Youden index was 0.944 and Kappa score was 0.95. Conclusions mNIHSS is an easy and reliable method in evaluating neurological function for supratentorial mass lesion patients when conducting sedation related neurological deficits researches, which showed a high sensitivity and specificity as well as good consistence with NIHSS.