A study by analytics firm MusicWatch reveals only half of those that signed up for a trial of Apple Music are using the service regularly.
Apple recently revealed that more than 11 million people sampled its new service free of charge, but MusicWatch claims that 48% of those have now stopped listening. Even among those who subscribed, 61% turned off the auto-renewal option.
The figures are disputed by Apple. The company said: "Of the people that have signed up for the trial 79% are using the service."
Two-thirds of the 5,000 Apple customers aged 13 and over surveyed said they were either "very likely" or "extremely likely" to pay for the music streaming service when their three month trial ends. That suggests many may have switched off auto-renewal in case they change their minds.
The auto-opt-in, media analyst Mark Mulligan says, means Apple could have around 8.7 million paying subscribers by the end of the year. That figure, however, would represent significantly less than the 20 million customers currently paying for the premium service on Spotify.
The report also noted that the arrival of Apple Music has not had a detrimental impact on the number of people buying music downloads.
MusicWatch managing partner Ross Crupnick said: "While it has become popular to use the term 'streaming wars' to characterize the current state of the music industry, very few Apple Music users said they had stopped using their online radio, audio on-demand or video streaming services, as a result of using Apple Music."