Purpose. We investigated the relationship between selected variables of anthropometry and training with race performance during a 26.4 km open-water ultra-endurance swim at 23°C in male master ultra-swimmers. Basic procedures. Fifteen non-professional male open-water ultra-endurance swimmers who were (mean ± SD) 40.0 (8.2) years of age with 83.7 (10.3) kg body mass, 1.80 (0.08) m body height and a BMI of 25.5 (2.5) kg/m2 finished the race within the time limit. Body mass, percent body fat, thickness of 7 skin folds, body height, length of arm, and length of leg were measured prior to race. The number of years as active swimmer, average weekly training volume in hours and kilometres and average speed in training were recorded. The variables were then correlated to total race time. Main findings. Study participants had mean finish times of 551 (100) min and an average speed of 3.0 (0.5) km/h. Speed in swimming during training was the only variable related to total race time (r = -0.66, p = 0.0037) whereas none of the other investigated variables showed an association. Conclusions. We conclude that anthropometry was not related to race performance in these male ultra-endurance swimmers whereas speed in training showed a moderate association with total race time.