Several expressions have been used to estimate global solar radiation from sunshine hours for weather stations in Oman, an arid region. These included original (linear) and modified (linear-logarithmic) Angstrom-Black type regression functions, a quadratic function, a power relationship, a power-trigonometric equation and one from a new Angstrom-Black type logarithmic model. For the power-trigonometric model, the solar altitude of the station was used as additional information for estimating the solar radiation. All the models performed well as estimators of global solar-radiation from sunshine hours but the non-linear models were better than the basic linear model. The power-trigonometric model estimated the radiation values best. The quadratic and linear-logarithmic models are the preferred models when only the relative sunshine is used.