Aluminium-copper of (99.99%) high purity eutectic alloy was melted in a graphite crucible under vacuum atmosphere. This eutectic alloy was directionally solidified upward with a constant growth rate V, and different temperature gradients G, and also with a constant temperature gradient and different growth rates in the Bridgman type directional solidification furnace. The lamellar spacings lambda(E) were measured from both transverse section and longitudinal section of the specimen. The undercooling values Delta T were obtained by using growth rate and system parameters K-1, K-2. It was found that the values of lambda(E) decreased as V, G and GV values are increased. The relationships between lamellar lambda(E)(2)V spacing lambda(E) and solidification parameters, V, G and GV were obtained by Least squares analysis. Bulk growth rate lambda(E)(2)V, was determined by using lambda(E) values for both the transverse section and the longitudinal section. The experimentally obtained values found were in good agreement with theoretical values.