The objective of the present research was to study the effects of row spacing on yield and seed quality of early maturity soybean cultivars in late planting. Three experimentS were carried out under field conditions, on a Ultisol (Terra Roxa Estruturada), in Botucatu, São Paulo State, Brazil. Soybean was planted in the second fortnigh of December (12/17/84, 12/30/84 and 12/27/85). In each experiment three early cultivars, i) IAC-Foscarin 31, ii) Paraná, and iii) IAS-5 were grown in three row spacing, namely, 0.40, 0.50 and 0.60m, with a uniform population of 500.000 plants/ha. The effects on yields, 100 seeds weight, germination and vigour of the seeds (by germination first-count, rapid aging and percentage of emergence of seedlings) were evaluated. The seed yields were not affected by row spacing. Cv. IAS-5 presented the highest yield in two experiments where a difference among cultivars was observed. The 100 seeds weight was greatest in the row spacing of 0.60m whenever a significant difference was detected. When the germination and vigour of seed were affected by row spacings, the worst quality of seeds was obtained in the row spacing of 0.60m, with exceptions for some tests. The cv. IAC-Foscarin 31 presented seeds with the best germination and vigour, and cv. Paraná produced seeds with the iowest 100 seeds weight.