  A precision test of lepton universality by measurement of the ratio RK of
K-->e nu to K-->mu nu decay rates was performed using a sample of 59963 K-->e
nu candidates with 8.8% background contamination collected by the CERN NA62
experiment. The result RK = (2.486 +- 0.013)*10^{-5} is in agreement with the
Standard Model expectation.
