A prospective study of group B streptococcal vaginal carriage among 225 Nigerian pregnant women in labour at UCH, Ibadan during a 3 month period in 1980 revealed a vaginal carriage rate of 19.5%; 8.9% of the 224 infants of the 218 infant-mother pair studied were colonized at birth. A significant proportion of the colonized mothers were primigravidas but no significant association was found between vaginal colonization and premature onset of labour, prolonged rupture of membranes, prolonged labour, stillbirth rate or puerperal infection. None of the twenty colonized infants developed "early" or "late" group B streptococcal disease on 3 months follow up. These results suggest the incidence of group B streptococcal disease in the newborn in Nigeria may be low despite high vaginal carriage rate.