Copolymers of 2-isopropyl- (iPrOx) and 2-n-propyl-2-oxazoline (nPrOx) were obtained, and attempts to control their crystallization both in condensed state and in solution were made. The homopolymer of nPrOx showed a weaker crystallization tendency than PiPrOx; nevertheless, the frequently encountered assumption that it is completely amorphous and is not able to crystallize was found to be unjustified. By increasing the amount of nPrOx in copolymers, their crystallization ability decreased both in the condensed state and in solution. The highest degree of crystallization was achieved for copolymer iPrOx/nPrOx of the composition 85:15 mol %, and chi(c) values of similar to 60% in condensed state and similar to 45% in water were obtained. On the other hand, for the copolymer with 50 mol % of nPrOx no crystalline fraction was observed, even when it was subjected to mild thermal treatment, both in the condensed state and in solution. However, when copolymers were subjected to more rigorous external conditions, such as exposure to high, predefined temperature for a significantly extended time, the crystallization of seemingly amorphous copolymer could be forced.