Twenty-four consecutive patients in an in vitro fertilization program were scanned within 1 hour of laparoscopic follicular aspiration. Twelve patients had follicles with intrafollicular echoes (group 1), and 12 patients had follicles with no changes (group 2). All women in group 1, but only four in group 2, had mature oocytes that after fertilization had cleavage rates compatible with pregnancy. Six clinical pregnancies occurred in group 1, and none occurred in group 2. The presence of intrafollicular echoes may indicate follicular maturation and may be a useful predictor of a cycle likely to produce a pregnancy.