A field experiment was conducted at Agricultural Research Farm, Narayan Institute of Agricultural Sciences, Gopal Narayan Singh University, Jamuhar, Sasaram, Rohtas, (Bihar) during the rabi (winter) season of 2022-2023 to access the effect of different varieties and spacing on growth and yield of mustard. Treatment consisted of three varieties RH- 404, DRMR-1165-40 and NRCM-101 and three spacing viz. 30×10 cm, 40×10 cm and 50×10 cm. Experiment was conducted under randomized block design with three replications. The result showed that growth viz. plant height, dry weight and yield attributes viz, number of siliqua/plant, length of siliqua (cm), test weight, grain yield (kg/ha) and harvest index (%) and yield were significantly affected due to different treatment combination. The maximum plant height (179.60 cm), dry weight (38.49 g/plant) at harvest, number of siliqua (395.33/plant), length of siliqua (6.54 cm), test weight (6.50 g), grain yield (2286.67 Kg/ha) and harvest index (34.80 %) was recorded in treatment combination of NRCM-101 + 40 cm × 10 cm.