A Region of interest(ROI) image coding method based on partial bitplanes alternating shift(PBAShift) is presented.Four strategies are introduced to improve the coding efficiency.First,the most significant bitplanes of ROI are shifted upon the maximum bitplane of background(BG).It can ensure the most significant bitplanes of ROI are firstcaoded.Second,the most significant bitplanes of BG coefficients and the general significant bitplanes of ROI are shifted up by bitplane-by-bitplane alternating scaling.Third,the general significant bitplanes of BG and the least significant bitplanes of ROI are obtained in the original positions.Finally,the least significant bitplanes of BG are shifted down.The experiments show that the PBAShift supports not only arbitrary shape single ROI coding without any ROI shape information,but also multiple ROIs coding with different degrees of interest.So the new method is valuable for medical and remote sensing image compression.