Fibreoptic bronchoscopy (FOB) is now commonly performed, and the number of elderly patients undergoing the procedure is increasing. Problems with oxygenation during FOB are well-recognised, but there are few data about its cardiovascular effects. Forty five patients (median age 65 yrs) undergoing elective FOB were studied prospectively. Patients were connected to a 12-lead computerized electrocardiographic recorder, a finger plethysmographic blood pressure (FPBP) monitor and pulse oximeter. Forty three patients were sedated with fentanyl and droperidol, and all were given 5 mL 2.5% cocaine intratracheally and xylocaine spray to the pharynx. Mean sphygmomanometric cuff blood pressure was raised initially (167/88 mmHg). Mean blood pressure recorded by FPBP rose on intratracheal injection (178/96 mmHg) and remained high throughout the procedure. Mean (SD) initial cardiac frequency was 93 (5.1) beats x min(-1) and rose to 134 (7.5) beats x min(-1) during the procedure. Four of the 45 patients showed unexpected ST segment depression of >1 mm for >1 min, and a further three developed bundle branch block. These seven patients had significantly greater tachycardia (152 vs 131 beats x min(-1)) and higher blood pressure (238/131 vs 207/109 mmHg). They were older (72 vs 61 yrs), had smoked more (63 vs 39 pack-years), but had similar lung function and similar changes in oxygen saturation. Oxygen desaturation occurred in 19 patients and this was associated with poor lung function (69 vs 84% predicted forced expiratory volume in one second), but was independent of the cardiovascular changes. Significant cardiovascular changes occur during fibreoptic bronchoscopy, with evidence of cardiac strain in 21% of patients over the age of 60 yrs.