Optical fiber having a glass portion; at least one protective coating of thermoplastic material having at least one thermoplastic elastomer; the thermoplastic material having the following characteristics: a modulus of elasticity value at +25.degree. C. lower than 150 MPa, preferably at least 10 Mpa, more preferably higher than 20 Mpa, and a Vicat point higher than 85.degree. C., preferably higher than 120.degree. C., more preferably lower than 350.degree. C. Preferably, the coating is a single protective coating directly positioned onto the glass portion.