In addition to the good adaptation of high temperatures and poor soils, cowpea (Vigna unguiculata L.) can be a good source of forage for livestock. This study was carried out to determine seed yield and some agronomical parameters of cowpea grown in different row spaces as double crop in Samsun ecological conditions. In the experiment, forage cowpea cultivar Ulkem and Line H-8 grown in four row spaces (20, 35, 50, 65 cm) in a Randomized Split Block Design with three replications. Seeds were sowed after harvesting wheat at July 13, 2017 and 15 July 2018. Seed harvest was made at October 20, 2017 and November 5, 2018. The results showed that seed yields ranged from 765 to 2178 kg ha-1 in 2017 and 397 to 1464 kg ha-1 in 2018. 1000 seed weight ranged from 161.17 to 183.93 g in 2017 and 146.40 to 160.90 g in 2018. In 2017 and 2018, mature pod ratio were 65.7 – 85.8, 30.0 – 60.3% respectively. Pod number per plant was between 5.66-15.00 pods/plant in 2017, 9.50-16.25 pods/plant in 2018. Seed number per pod was ranged from 8.80 to 12.43 seeds/pod in 2017, from 8.00 to 11.50 seeds/pod in 2018. Though the highest seed yields were obtained from 20 cm row space, it is risky cultivated cowpea for seed production as double crop in Samsun conditions because of earlier autumn rainfall and high humidity.