Purpose. In long-distance runners, an association between skinfold thicknesses and running performance has been demonstrated. Basic procedures. We investigated the relationship between skinfold thicknesses and race time in cyclists in an ultra-endurance cycling race. In 28 ultra-endurance cyclists at the ‘Swiss Cycling Marathon’ over 600 km, skinfold thickness at 8 sites was measured pre race. Single skinfold thicknesses, the sum of 8 skinfolds and percent body fat were correlated with total race time. Main findings. The cyclists finished within 1.596 (296) min riding at an average speed of 26.8 (5.7) km/h. There was no correlation between single skinfold thicknesses, the sum of 8 skinfold thicknesses and percent body fat with total race time. Conclusions. In male ultra-cyclists in a 600 km ultra-marathon, no correlation between skinfold thicknesses and race performance has been detected as demonstrated in long-distance runners.