Recurrent respiratory symptoms in the first year of life following preterm delivery were documented in two studies. In the first study a questionnaire was sent to all parents of preterm very low birth weight (VLBW) infants who had been admitted during a six-month period to the Neonatal Intensive Care Unit (NICU) at King's College Hospital (KCH) and who lived within the local district. Questionnaires were also sent to parents of a control group of infants who were recruited by random selection. All the controls lived locally and were delivered at KCH in the same six-month period as the study group, but were born at 37-41 weeks of gestation and had had no neonatal problems. The questionnaire documented frequency of cough and wheeze, medication and hospital admissions. Recurrent respiratory symptoms (wheeze or wheeze and cough) occurred in 65% of the preterm VLBW infants but only 33% of the controls p less than 0.001. Less than 10% of infants in either group had received bronchodilator therapy. Admission to hospital in both groups was more common amongst children who had recurrent wheeze (p less than 0.01). In the second study all preterm VLBW infants admitted to the NICU in a six-month period were followed prospectively over the first year of life. The nature and frequency of respiratory symptoms and frequency and length of re-admission was documented and related to the duration of neonatal ventilation. Twenty-three of the 44 preterm VLBW infants (53%) followed prospectively had recurrent wheeze and/or cough.(ABSTRACT TRUNCATED AT 250 WORDS)