The Serie A giants have the option to make the deal for 23-year-old permanent at any point during the season.
The Egyptian international did not see much action during Chelsea’s Premier League title run.
He made only three appearances for the Blues last season while spending the majority of the 2014-15 season on a loan deal with Fiorentina.
Salah showed much more promise during his Serie A stint, scoring nine goals in 26 appearances for La Viola.
This will undoubtedly make it tempting for Roma to permanently buy the Egyptian winger.
Salah was signed by Chelsea from Swiss club Basel for £11m in January 2014.
The Blues are looking to defend their Premier League title with Diego Costa and Eden Hazard once again shouldering the goalscoring load for the London club.
It remains to be seen whether they will hold onto Salah if he can continue to showcase his potential in Italy.
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