Sixty growing New Zealand white rabbits aged four weeks were used in this study to assess the effect of age and two feed additives on some fiber traits and skin follicles characteristics. The experiment continued for one month to the age of eight weeks. Rabbits were randomly divided to three groups; the first group was control fed on concentrated pellet, the second group was supplemented with Micronil (1 ml/L of drinking water) as an antimicrobial antifungal compound while the third group was provided with Turbocal forte (1ml/L of drinking water) as a source of minerals and trace elements. At four, six and eight weeks of age, five rabbits from each group were weighed, skin biopsy was obtained from the right flank of each animal and hair samples were removed by a sharp clipper. Skin samples were examined to study the effect of age and treatments on skin follicles characteristics and fiber diameter. The results showed that external diameter, internal diameter, fiber diameter of the primary and secondary skin follicles and S/P ratio increased (P<0.05) at six weeks of age. Wall thickness of primary and secondary follicles increased (P<0.05) at eight weeks of age. The prickle factor increased (P<0.05) with age advance. It accounted for 2.27, 4.68 and 4.67 (%) at four, six and eight weeks, respectively. It seems that there is a critical growth period at the age of six weeks in which the fiber length decreased and the fiber diameter increased. Micronil supplementation decreased (P<0.5) external diameter, internal diameter and fiber diameter of the primary and secondary skin follicles as well as the wall thickness of the primary follicles. Turbocal forte supplementation decreased (P<0.05) the external diameter and the wall thickness of the primary follicle and the fiber diameter of the secondary follicles. Both types of supplementation increased (P<0.05) the average fiber length compared with the control group.