Abstract: A medical electrical lead having an elongated lead body carrying a conductor therein, the lead body being formed of an inner sleeve of a first, relatively more rigid plastic and an outer sheath of a second, relatively less rigid plastic, the inner sleeve having a tubular portion and having outwardly extending helical ridges extending along its length, the ridges having lateral wall surfaces extending radially from the tubular portion and an outer sheath over the inner sleeve and in contact with the lateral wall surfaces of the inner sleeve. A fixation helix may be mounted at the distal end of the lead body and a conductor, which is also rotatable relative to the lead body may be located within the inner, tubular sleeve. Conductors may also be located between the ridges of the inner sleeve, embedded in the outer sheath.