Reliability and stability of neurological "subtle" ("soft") signs were assessed in 54 psychiatric patients and 25 normal children, aged 5-17 years, using the revised Neurological Examination for Subtle Signs (NESS). Acceptable interrater reliability (kappa greater than or equal to 0.50, or intraclass correlation coefficient greater than or equal to 0.70) was found for 40 of the 64 items tested. Test-retest reliability at 2 weeks was unsatisfactory for most of the categorically scored items, including some "classic" subtle signs such as overflows or dysrhythmias. Continuous items, such as time needed to perform 20 consecutive movements, remained mostly stable at retest. A practicing effect was evident only in the graphesthesia test. Overall internal consistency was good (Cronbach's alpha = 0.74). Given the poor stability of overflows and dysrhythmias, researchers and clinicians should rely more on subtle signs that can be assessed on continuous scales.