A study was conducted to evaluate effects of an Aspergillus niger mycelium, antibiotic and probiotic on growth performance, P and Ca retention and Clostridium perfringens ileal counts in broiler chickens. Chickens were fed maize-wheat-soyabean meal diets from day 1 to 21. Dietary treatments included: 1. a low phosphorus diet (LP), 0.17% nonphytate phosphorus, 0.6% Ca; 2. LP + virginiamycin; 3. phytase diet (Phyt), LP + 750 phytase units/kg diet; 4. Phyt + virginiamycin; 5. fungal mycelium diet (Myc), LP + 1.5% mycelium; 6. standard phosphorus diet (SP), 0.41% nonphytate phosphorus, 0.87% Ca; 7. SP + virginiamycin; 8. probiotic diet (Pr), SP + probiotic; 9. high phosphorus diet (HP), 0.45% nonphytate phosphorus, 1% Ca; 10. HP + virginiamycin. Each diet was fed to fve pens replicates of eight birds each from hatch to 21 day of age. Chickens receiving Myc, Pr, both HP, and both SP diets performed better than birds fed both LP and both Phyt diets and showed the highest bone mineralization. The lowest intestinal viscosity (1.53 mPa·s) and the highest phosphorus retention (62.1%) was observed in birds fed diet supplemented with fungal mycelium. Birds fed Myc, Pr, both SP and both HP diets showed the highest calcium retention that did not differ from each other. Antibiotic was the most effective in reducing C. perfringens counts in ileal digesta. The study confirmed a high efficacy of A. niger mycelium used at the level of 1.5% in enhancing growth performance and P retention in chickens.