The decay K+->pi+nunu has a very precisely predicted branching ratio (BR) of less than 10^-10 and is one of the best candidates to reveal indirect effects of new physics at high mass scales. The NA62 experiment at CERN SPS is designed to measure BR(K+->pi+nn) with in-flight decays, a novel technique for this channel. NA62 took its first physics data in 2016, reaching sensitivity to the decay at the Standard Model BR. The experiment collected 10 times more statistics in 2017 and a similar amount of data is expected from the 2018 run. The preliminary result on K+->pi+nunu from the full 2016 data set will be presented and prospects for future improvements will be discussed.