Over 15 million tons of fly ash (FA) and 3 million tons of phosphogypsum (PG) are produced in Turkey every year. The utilization of these industrial by-product materials is important in terms of environmental and economical issues are concerned. The main purpose of this study is to evaluate the technical possibilities of incorporating FA and PG in production of building blocks. Various mixtures were prepared by incorporating these industrial wastes by replacing clay with seven different weight proportions (0%, 5%, 10%, 15%, 20%, 25% and 30%). All specimens were fired at 1000 • C peak temperature. The physical and mechanical properties of all specimens such as; unit weight, compressive strength, flexural strength, dimensional stability and water absorption values were recorded. The effect of PG incorporation on the properties of samples seems to be more dominant than the effect of FA incorporation. The test results showed that; PG incorporation increased the unit weight and mechanical strength values while lowering the water absorption values. Utilization of these wastes additives is not only for conservation of clay resources, but also an alternative solution to a difficult and expensive waste disposal problems.