Drosophila subobscura is a species with a rich chromosomal polymorphism for inversions. Evidence demonstrates that it is adaptive. In the present research, we studied whether it is possible to detect changes in the inversion chromosomal polymorphism of D. subobscura in a medium-term period of time. The Serbian population of Avala was selected and its inversion composition in 2004 and 2011 (a seven year period) was compared. Significant variation was found in the U chromosome. This result was due to a significant increase of U1+2 (warm) and a decrease of Ust (cold) and U1+2+6. Further, minimum, maximum and mean temperatures increased (although not significantly). Thus, U chromosome seems to be able to react in a medium-term to temperature changes in the way expected by the global warming.