The research was carried out on 12 pigs: 8 castrated males and 4 whole females belonging of autochthonous genetic types (AGT) Calabrese (n equal to 4), Cinta casaldianni (n equal to 2), Cinta senese (n equal to 2) and Siciliano (n equal to 4). On Longissimus dorsi (LD) and Psoas major (PM) muscles the morphometric characteristics of FG (fast glycolytic), FOG (fast oxidative glycolytic) and SO (slow oxidative) fibre types and their percentage were determined. However the area of adipocytes from internal and external layer of adipose tissue from pig back fat, shoulder, dorsal and loin regions, was also determined. The results have showed that: (i) as regards muscle fibres, the SO is larger than FG and FOG ; (ii) the size of FG fibre is significantly different among the 4 considered AGT ; (iii) Longissimus dorsi muscle is characterized by FG and SO fibres twice larger than PM and (iv) there are no significant differences between sexes for size of three fibre types.