Fully three-dimensional image reconstuction is a major challenge for new tomographic devices in radiology and nuclear medicine. The use of a 2-D detector such as a radiographic image intensifier or an Anger camera provides series of 2-D projections which are processed by the reconstruction software to compute the unknown 3-D image. In cone-beam geometry, all the projection lines converge to a same focal point. This geometry provides a zoom effect. But dedicated reconstruction algorithms are needed since a given line crosses several volume slices. In this chapter, we give an overview of cone-beam reconstruction algorithms, with a special emphasis on transform methods and in particular on indirect algorithms via the Radon domain. We summarize the mathematical framework, and we provide some experimental results using the RADON software. Next, we consider two specific research topics in cone-beam reconstruction which are the processing of the shadow zone in the Radon domain associated with a circular acquisition trajectory and the reconstruction of a region of interest within the object using either a dual magnification acquisition or a multifocal geometry.