['Previous studies have indicated that the increased airway resistance that develops in asthma may partly be due to a surfactant dysfunction. If so, it might be possible to alleviate the acute signs following an allergen challenge by prophylactically instilling into the airways a well functioning pulmonary surfactant.', 'The study was planned and enacted to test the above hypothesis.', 'The lung function (airway resistance, tidal volume, minute ventilation, and dynamic compliance) of 22 immunized guinea-pigs was studied for 30 min following a challenge. Ten of the animals had received a tracheal instillation of 0.5 mL calf lung surfactant extract (CLSE, 35 mg/mL) prior to the challenge.', 'The animals receiving the dose of 17.5 mg surfactant were less affected by the challenge than were the controls. Only one of them died following the challenge, whereas four of the 12 controls succumbed. Lung function was significantly less affected among the nine surviving animals treated with surfactant prior to the challenge than among the eight surviving controls (P < 0.01) and also their blood gases (pCO2 and pO2) were less influenced (P < 0.05).'] Does pulmonary surfactant given prophylactically alleviate an asthma attack in guinea-pigs?