Control of nosocomial group B streptococcal (GBS) colonization of newborn infants was attempted in a four-cycle study alternately employing single applications of povidone-iodine (iodophor) and triple dye to the umbilical cord stump and periumbilical area. GBS colonization rates were 49% and 34% following iodophor cord care (cycles II and III) and 11% and 50% following triple dye cord care (cycles II and IV). The apparent significant reduction of GBS colonization during triple dye cycle II could not be reproduced in a subsequent follow-up culture survey and remains unexplained.