A field experiment was conducted during kharif season of 2009 on fodder amaranth (Amaranthus spp.) to study the effect of row spacing and seed rate on growth and fodder productivity of amaranth genotypes in clay soil under rainfed condition at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad (Karnataka). There were eighteen treatment combinations consisting of two row spacing (30 &45 cm), three genotypes (Suvarna, GA-1 & SKNA-504)and three seed rate (2.0, 2.5 & 3.0 kg ha-1). The row spacing of 45 cm recorded significantly higher green forage yield (36.77 t ha-1), higher dry matter yield (2.33 t ha-1) as compared to 30 cm row spacing. Among the genotypes, GA-1 produced significantly higher green forage yield (37.64 t ha-1) and dry matter yield (2.59 t ha-1) as compared to Suvarna and SKNA-504. Seed rate of 2.5 kg ha -1 produced significantly higher green forage yield (36.30 t ha-1) and dry matter yield (2.33 t ha-1) as compared to 3.0 kg ha-1 seed rate, where as 2.5 kg ha-1 seed rate was on par with 2.0 kg ha-1 seed rate. In interaction Significantly higher green forage yield (43.53 t ha-1) and dry matter yield (3.01 t ha-1) was recorded in 45 cm row spacing, genotype GA-1 with seed rate of 2.5 kg per ha and higher net returns (` 23,410 ha-1) and benefit cost ratio (3.53) was obtained with genotype Gujarat Amaranth-1 (GA-1) with 45 cm row spacing @ 2.5 kg per ha seed rate.