The growth of 32 extremely low birth weight infants (1000 gm or less) was determined at adolescence. Their height, weight, and head circumference were measured twice in the first year of life and then at ages 2, 3, 5, 8, 10 years, and during adolescence (12 to 18 years). The mean height, weight, and head circumference of the adolescents were at the 50th percentile. Female heights were > or = their mothers; male heights were in the same or greater percentile than those of their fathers. Extremely low birth weight infants experience "catch-up" growth up to and into adolescence and attain predicted biparental genetic height.