This study was conducted to investigate the effects of age and sex on the fleece characteristics of 40 Iranian indigenous Khorasan goats. Goats were divided into two different sex and age (kids and adults) groups. Fiber characteristics under study were: fleece weight, fiber length, lock length, fiber diameter, coefficient of fiber diameter, breaking load, resistance, elongation, hair percentage and down fibers percentage. The results showed that sex and age had a significant effect on fleece weight and fiber diameter. The average fleece weight was 214.6 ± 0.5 g in males and 186.9 ± 4.15 g in females while 196.2 ± 15.8 g in kids and 205.5 ± 15.8 g in adults. The average fiber diameter was 88.4 ± 4.5 microns in males and 73.5 ± 3.9 microns in females while 73.4 ± 3.9 microns in kids and 88.5 ± 4.5 microns in adults. The resistances of hair in kids (8±0.9 grf/t) were lower than in adult goats (10.5±0.7 grf/t). Fleeces had down fibers (1-30% with the average amount of 11.1%±2.2), average fiber diameter of 16.4 ± 0.6 micron and coefficient of variation of fiber by 18.3 ± 1.1%. The correlation between fiber length and lock length, resistance and lock length were 0.9 and 0.6, respectively which was considered highly positive. In the overall view, according to the approximately low fleece weight, low fiber length and including of down fibers in the fleece of indigenous Khorasan goats, they are categorized in hair goats with medium quality fleeces. Manuscript profile