This research investigates the effect of the different types of low, middle and high clouds on the intensity of solar radiation received from these clouds in Mosul City during the winter and spring months of the year 2004-2005. The effect of the different types of clouds on the transmissivity of solar beam was studied. The results showed that the transmissivity ranges from 82% for high clouds, from 49% to 55% for middle clouds and from 19% to 21% for low clods. Linear relationships have been established between the transmitted solar radiation under the different types of clouds and the intensity of solar radiation under cloudless skies. These relations were tested using independent data and they gave a good accuracy. The results also showed that low and middle clouds have a serious effect in the reduction of solar radiation passing through it.