This paper is concerned with the proper placement of gels to reduce fluid channeling in reservoirs. Previous work demonstrated that an acceptable gel placement is much more likely to be achieved in a linear flow geometry (e.g., vertically fractured wells) than in radial flow. In radial flow, oil-productive zones must be protected (e.g., using zone isolation) during gel placement to prevent damage to oil productivity. In this study. two theoretical models were developed to determine water injection profiles before and after gel placement in anisotropic reservoirs-where the effective permeability and/or the pressure gradient are greater in one horizontal direction than in another direction. The primary question addressed in this work is, how anisotropic must an unfractured reservoir be to achieve an acceptable gel placement and profile modification during unrestricted gelant injection? Both analytical and numerical methods were applied to solve the problem. We studied how the effectiveness of gel treatments is influenced by permeability variation, distance of gelant penetration, anisotropic pressure distributions, resistance factor, and residual resistance factor. Our analyses showed that the range of permeability variations (permeability in the most-permeable direction divided by permeability in the least-permeable direction) must be greater than 1,000 (and usually greater than 10,000) before anisotropy call be exploited to achieve a satisfactory gel placement in unfractured wells. We doubt that any unfractured wells or reservoirs exist with this degree of anisotropy. In contrast. in wells acid reservoirs where anisotropic flow is due to fractures, the linear flow geometry and the extreme permeability contrast between the fracture and the porous rock can aid gel placement substantially.