Most neonatologists in the United States provide full resuscitation in delivery room to all extremely low birth weight [ELBW, < 1000 grams] babies believing that these infants will 'declare themselves' in the first couple of days of life. Meadow et al in 1996 analyzed the survival rates of 429 ELBW babies born in our NICU for three years. They showed that about 80% of ELBW deaths occurred in the first three days of life. Once an infant had survived to the fourth day of life, the likelihood of survival to discharge was about 81%. The aim of our study was to develop birth weight-specific survival curves for ELBW infants to be used as an instrument for predicting the chance of survival for infants in a given birth weight group on a given day of life. Using United States data in 1991, we estimated race-specific Kaplan-Meyer survival curves with 95% confidence bands based on Greenwood formula for 13,994 ELBW babies with birth weights 500 to 1000 grams in 100 grams increments. Results showed that in all birth weight groups the greatest drop in survival occurred in the first day of life and that the survival curves became fairly flat afterwards particularly for infants with higher birth weights. Babies who were alive on the fourth day of life had the following survival rates in different birth weight groups: 1) 500-600 grams, 64% survival rate [95% C.I., 60 - 67%], 2) 600-700, 74% survival rate [95% C.I., 72-76%], 3) 700-800 grams, 82% survival rate [95% C.I., 80-84%], 4) 800-900 grams, 88% survival rate [95% C.I., 87-89%], 5) 900-1000 grams, 90% survival rate [95% C.I., 89-91%]. Babies in birth weight group 500-600 grams had 80% survival rate [95% C.I., 77 - 83%] if they were alive on day of life 18 and babies in birth weight group 600-700 grams had 80% survival rate [95% C.I., 78-82%] if they were alive on day of life 13. We suggest that birth weight-specific survival curves for ELBW infants can provide useful information on chance of survival for infants in a given birth weight group on a given day of life.