The improvement of impact sound insulation of floor coverings can be measured in the laboratory according to the standard ISO 10140. At present, ISO 12999-1 gives standard uncertainties for the reduction of impact noise by floor coverings at reproducibility conditions only. To evaluate both the repeatability and reproducibility of the test method, a round robin test was set up by the WG Acoustics of ENBRI (European Network of Building Research Institutes). Each of the 9 laboratories involved received 3 samples cut from the same vinyl floor covering and performed 4 tests. The reproducibility standard deviations of the round robin test agree well with the ISO 12999-1 values at low frequencies, but are significantly larger from 500 Hz upwards. The influence of sample variability seems to be negligible. In most frequency bands, the repeatability standard deviation is lower than the ISO 12999-1 standard uncertainty for impact sound insulation at repeatability conditions.