Images are very important forms of data that are widely used nowadays. Every day, millions of grey and color images are transferred via the web. Protecting these images from unauthorized persons is an important issue. Image encryption is one of the image-securing techniques. One advantage of using encryption is that the plain image is converted to an unrecognized one. Also, the plain image is restored without any loss of information. In this paper, a color image encryption technique using blocks scrambling and chaos is presented. First, the plain image is decomposed into three channels: R, G, and B. Then, each channel is divided into sub-images and blocks. Our encryption algorithm depends on two main steps: scrambling and diffusion. First, the pixels’ arrangement in sub-images and blocks is changed, and then scrambling between sub-images is done to get the scrambled image. Then, in diffusion, the scrambled image diffuses using the logistic map to get the encrypted image. The experimental results show that our proposed algorithm has good performance in encrypting color images.