Field experiment were conducted during rainy (kharif) season of 2009 and 2010 to study the effects of various spacing and topping practices on growth and seed yield of sunnhemp. Spacing (30 × 10 cm, 30 × 20 cm, 45 × 10 cm and 45 × 20 cm) in main plots and topping (no topping, topping at 30 days after sowing and topping at 45 days after sowing) in sub plots were studied in split plot design with three replications. The individual plant performance with respect to plant height, basal diameter, dry matter accumulation, number of branches and yield attributes was found maximum under the spacing of 45 × 20 cm whereas total biomass and seed yield per unit area was obtained highest with the spacing of 30 × 10 cm. Topping at 30 days after sowing gave higher yield attributes and seed yield being at par with topping at 45 days after sowing. Thus sunnhemp grown at the spacing of 30 × 10 cm coupled with topping at 30 days after sowing realized higher yield. Key words: Sunnhemp, spacing, topping, seed yield.