The former Spanish international captain will turn 37 years old shortly before the season is about to end, and although happy with life at Bolton he says that he may hang up his boots in 2005.
"I happy playing in Bolton after the pressure of the years at Real Madrid," Hierro told Marca.
"Each day I am content by my move to England. It is very probable that this year is the last of my career."
Hierro began his glittering career back in 1987 as a raw teenager with Real Vallodolid before his performances took him onto the bigger stage at Real Madrid in the summer of 1989.
He was to spend 14 years of his career at the Bernabeu in an exceptional period which was to see him win a flurry of medals which included the La Liga Championship on numerous occasions as well as four Champions League medals.
From there then followed a year long spell in Qatar with Al-Rayyan before linking up with Wanderers this summer were he has become a popular and valuable squad member.