Abstract: A field experiment was conducted at the Research farm, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh, during the period from November 2011 to April 2012 to study the effect of spent mushroom substrate (SMS) and cowdung on growth, yield and proximate composition of brinjal (BARI Begun-6 and BARI Begun-8). Experiment was comprised of 5 treatments with three replications. The highest plant height (80.11cm, 75.56 cm), branch per plant (16.47, 18.80), the lowest days to first flowering (70.47 days, 70.20 days), the highest number of fruit per plant (7.4, 20.47), weight of individual fruit (262.3 g, 70.99 g), yield per plant (1.938 kg, 1.452 kg) and yield per ha (41.03 tons, 30.73 tons) were recorded in T3 treatment for BARI Begun-6 and BARI Begun-8 respectively. In BARI Begun-6 and BARI Begun-8, the highest dry matter (7.59 %, 8.60 %), carbohydrate (3.46%, 4.07 %) and lipid (0.367 %, 0.425 %) were recorded in T1 whereas the highest crude fiber (2.15%, 2.34 %) and protein (1.323 %, 1.42 %) were obtained in T3 treatment and the highest ash content (0.337 %, 0.41 %) were found in T2 treatment. On dry weight basis, in BARI Begun-6 and BARI Begun-8, the highest amount of Zn (1.879 mg %, 1.903 mg %) and Na (36.50 mg 536.69 mg %) was recorded in T1 treatment whereas the highest P (272.6 mg %, 277.3 mg %), Ca (239.7 mg %, 235.4 mg %) and Fe (3.21 mg % 3.021 mg %) were found in T2 and the highest K (282.4 mg) and Mg (186.4 mg %, 186.9 mg %) were obtained in T3 treatment. The highest K (282.4 mg) in BARI Begun-6 was obtained in T3 treatment and in BARI Begun- 8, the highest amount K (288.3 mg %) was obtained in T2.