Director of the London clinic says that Manchester United star Rooney's grey hair is perfectly normal and temporary.
Fans were surprised by Rooney's appearance when he played for United's Premier League opener against West Bromwich Albion on Sunday after his 30,000 pound transplant to give himself back his full head of hair.
The 25-year-old's hair has lost some natural colour and faded to a light grey sparking fears that the transplant had failed, the Sun reports.
However, Harley Street Hair Clinic director Nadeem Uddin Khan said: "It isn't possible to judge the full effect of a transplant for at least 6-12 months."
"While the roots re-establish themselves, the growth on top can be patchy and this can involve some initial loss or discolouration. This is entirely normal and does not affect the ultimate outcome of a fully restored hairline," he added.