The changes of the moisture absorption qualities were investigated and the isotherms of sorption for tobacco were determined for the following origins: Krumovgrad, Nevrokop, Harmanli, Melnik, East Balkan and Djebel. Investigations were conducted at 21°C and for relative air humidity (R.H.) values of 58, 68 and 80%.The following results were obtained:- the humidity at equilibrium of tobacco at 58% R.H. is as follows: origin Krumovgrad 11,9-14,4%; Nevrokop 11,8-12,6%; Harmanli 11,6-13,0%; Melnik 11,2-12,2%; East Balkan 12,7-12,8% and Djebel 12,5-12,9%. Under such humidity at equilibrium tobacco loses its flexibility and strength and becomes very breakable;- the humidity at equilibrium of tobacco at 68% R.H. is: origin Krumovgrad 15,9-17,2%; Nevrokop 15,8-16,5%; Harmanli 15,0-15,4%; Melnik 15,6-16,0%; East Balkan 16,1-16,5% and Djebel 15,4-16,9%. Tobacco has the optimal flexible properties under these conditions which appear to be conducive to its storage.- the humidity at equilibrium of tobacco at 80% R.H. is: origin Krumovgrad 21,7-23,0%; Nevrokop 21,4-22,0%; Harmanli 20,6-22,8%; Melnik 20,8-21,5%; East Balkan 21,4-22,9% and Djebel 22,3-22,7%. Under such values of humidity at equilibrium tobacco gets mouldy.