<p>This study investigates the effect of combining natural and recycled fine and coarse aggregates on the compressive strength of concrete at 28 days. The relevance of this research stems from the growing volume of construction waste generated by building demolition and the need to reuse this material in the construction industry. The study aims to evaluate the effect of using recycled aggregates of various origins in concrete mixtures while ensuring adequate strength. Experimental studies were conducted under laboratory conditions by producing a series of cubic concrete specimens measuring 100×100×100 mm. A series of concrete mixes made with natural granite crushed stone and sand was used as a reference for comparison. In other series, the effect of partial and complete replacement of fine and coarse aggregates with crushed concrete, brick rubble, and crushed glass was investigated. Compressive strength was determined after 28 days of curing using a standard method. It was established that using crushed concrete as a coarse aggregate in a well-designed mix provides a strength level close to the baseline. Partial replacement of sand with crushed glass in the fine aggregate mixture results in a moderate decrease in strength; however, the resulting values remain sufficient for structural concrete. Using brick rubble as the sole coarse aggregate results in a significant decrease in strength. In contrast, its combination with natural crushed stone partially compensates for the negative effect of porosity. The lowest strength values were recorded for concrete using coarse-grained crushed glass. The results obtained confirm the feasibility of using recycled aggregates in concrete, provided that the mix design is properly selected and the gradation is controlled.</p>