An ethological approach was used to compare nonverbal behavior in infants aged six and 12 months with neurological problems from birth (ICD-10 P91.8; risk group) with the behavior of their healthy (normal group) peers. Assessment of the sequence and duration of behavioral elements displayed by the infants in the familiar home environment during day-to-day activity was performed on the basis of continuous observations using 1- and 2 min video recordings in double-blind conditions. We suggest that if there are characteristic behavioral differences, these should be regarded as prognostic markers for developmental problems in infants. Ethological analysis showed that the main behavioral differences were associated with the infants’ eye and hand activity. At both ages, infants of the risk group became distracted from objects held in their hands, looking away more often than infants of the normal group. Risk group infants aged 12 months demonstrated less exploratory activity than their healthy peers. These observations lead to the suggestion that short-term observations of nonverbal behavior can be used as a supplement to diagnostic scales for the rapid assessment of cognitive status in infants.