A study was conducted to clarify the exercise intensity and metabolic condition during a free routine of synchronized swimming with respect to heart rate (HR), blood lactate concentration (La) and the rate of perceived exertion (RPE) . Six well trained female synchronized swimmers participated as subjects. HR during the free routine was measured continuously. La and RPE during the free routine were measured intermittently from the start to end of each stage. Maximum heart rate (swimmingHRmax : S-HRmax) was determined by measurement of maximum oxygen uptake using a swimming flume. Peak blood lactate concentration (Peak La) was measured after the maximum front crawl stroke of 100 m. The average values and S. D. of S-HRmax and Peak La were 180.0±3.8 beats · min^-1 and 9.6 ± 1.0 mmol · 1^-1, respectively. Average values, S. D. and ranges of HR and %S-HRmax during the free routine were 137.6±25.5 (60-180) beats · min^-1 and 76.5± 14.3 (34.5-96.8) %, respectively. HR during the free routine showed a decrease in the breath-holding phase. Average values and S. D. of La, %Peak La and RPE at the fourth stage were 5.4±1.2mmol·1^-1, 57.0±17.2% and 17.7±0.8, respectively. La, %Peak La and RPE at the fourth stage were significantly higher than those at the other stages, and La, %Peak La and RPE at the third stage were significantly higher than those at the second stage. These results suggested that the overall intensity of the free routine was moderate, but that part of the free routine included high-intensity activity and the percentage of anaerobic metabolism during the free routine increased in the final stages