According to the commonest definition, infant colic is distinguished by crying which is 'paroxysmal'-that is, intense and different in type from normal fussing and crying. To test this, maternal reports of the distress type of 67 infants whose fuss/crying usually exceeded three hours a day ('persistent criers') were scrutinised using 24 hour audiorecordings of the infants' distressed vocalisation. 'Moderate criers' (n = 55) and 'evening criers' (n = 38) were also assessed. Most of the distress in all three groups was fussing. In the audiorecordings the persistent criers showed a higher crying: fussing ratio than the moderate criers, but intense crying was rare. A third of the persistent criers were reported by their mothers to have occasional, distinct colic bouts of 'intense, unsoothable crying and other behaviour, perhaps due to stomach or bowel pain.' In the audiorecordings these periods were longer, but not paroxysmal in onset or more intense than the crying of persistent criers not judged to have colic. The audible features of the crying may be less important than its unpredictable, prolonged, hard to soothe, and unexplained nature.