The paper presents a study on the process of formation of concentrated structure of raw hams and its transformation from the loose consistency, characteristic of raw meet, to that of dry cured hams, on the example of hams coming from two Polish primitive pig breeds: Puławska and Złotnicka. They were subjected to dry curing, preliminary ripening and final ripening until ready dry cured hams were obtained. Test samples were collected on days 0, 7, 13, 23, 35, 44, 52 and 59 of manufacture, after the hams reached 75% yield. The determination of water and total protein content was performed with the aim to calculate Feder’s number, being an index of muscular tissue rehydration. To study the development of texture in raw ripening hams during the manufacturing process, the modified CASRA method was applied. Manufacturing process of raw-ripening hams till obtaining the manufacturing level of 75% for hams coming from meat of the Puławska breed lasted for 52 days, with decrease of Feder’s number from 3.5 to 1.9, and for hams derived from the Złotnicka breed it amounted to 59 days, with decline of Feder’s number from 3.6 to 2.0. Together with increasing dewatering of muscular tissue, as expressed by decreased Feder’s number (water content to total protein content ratio) and increased salt level, loose consistency, typical of fresh raw meat, was changing into concentrated one, characteristic of solid body. The index characterising deformation at the lowest stress, Dmin, decreased from 40-45% in raw meat to the level of 8-10% in the final products. Together with the decrease of Feder’s number, the plasticity parameter increased by ca 2.0, while elasticity and fluidity decreased about two-fold. That was an evidence of development of concentrated ham consistency.