An analysis of the relationship of amniotic fluid shake test titers and the subsequent fetal lung maturity as evinced by the development of the respiratory distress syndrome (RDS) has been conducted. Over a four-year period, 131 amniotic fluid samples were tested within 48 hours of delivery. RDS was diagnosed in 16 infants. When the shake test was positive at a 1:2 dilution, one child developed a mild case of RDS (2.3%). If the test was positive at a 1:4 dilution, none developed RDS. RDS occurred in 15% of the cases with a positive test at a 1:1 dilution and in 30% of the cases with a negative test. This test has proved to be an excellent screening method for predicting fetal lung maturity if it is positive at 1:2 or greater. If the result is positive at a 1:1 dilution, or negative, other methods must be used for assessment. Its advantages are its rapidity, simplicity, and low cost.