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In Serbia, during the production of electricity and burning of lignite, about 6.5 million tons of waste fly ash are produced annually. During the production of phosphoric acid, about 810 thousand tons of waste phosphogypsum are generated. Available data indicate that about 5% of waste fly ash is recycled in cement production, while phosphogypsum is piled up in landfills. Both wastes contain an increased concentration of 226Ra activity, compared to the raw materials used for brick production. This paper deals with the investigation of the possibility of recycling these two wastes in the production of clay bricks in a radiologically acceptable manner. A total of 8 systems of brick samples were produced with a proportion of phosphogypsum in the range of 0-35% and fly ash in the range of 0-17.5%. The proportion of phosphogypsum in each investigated system was twice as high as the fly ash content. The gamma spectrometry method was used to determine the concentrations of 226Ra activity in raw materials and all brick samples. The measured concentrations of 226Ra activity are 536±20 Bq kg-1, 182±10 Bq kg-1, for phosphogypsum and fly ash, respectively. Measurement of radon exhalation was carried out using the RAD7 device. The values of surface exhalation rate and indoor radon concentration for a room of standard dimensions were estimated, after which the annual effective dose from radon inhalation was determined. Estimated values of indoor radon concentrations are acceptable and below 100 Bq m-3, which gave an annual effective dose of less than 1 mSv y-1. Bearing in mind that building material is not a dominant source of radon in ground rooms, this way of recycling the analyzed waste materials is acceptable with a lower proportion of phosphogypsum and fly ash. The higher content of these wastes in the brick also contributes to the higher content of 226Ra, which gives a significantly higher contribution to the total indoor radon concentration.