The Cd-67.8 wt.% Sn eutectic alloy was prepared by melting together appropriate amounts of cadmium and tin (both of 99.99% purity) in a graphite crucible in a vacuum melting furnace. Then, this eutectic alloy was poured into graphite crucibles in a hot filling furnace and the samples were solidified. These samples were directionally solidified upward with different growth rate ranges (8.1-165 mu m/s) at a constant temperature gradient G (4.35 K/mm) in the Bridgman type directional solidification furnace. The lamellar spacings were measured using directional solidified samples. The variations of lambda with respect to V were determined by using linear regression analysis. The dependence of lamellar spacings X. on undercooling, Delta T, was also analysed. The variations of Delta T with V (at constant G) were investigated. According to these results, it has been found that with the increasing values of V, lambda decreases, whereas, Delta T increases for a constant G.lambda V-2, Delta T lambda and Delta TV-0.5 values were determined by using x, AT and V values. The results obtained in this work have been compared with the Jackson-Hunt eutectic theory and experimental results studied by Borland and Elliott, Clark and Elliott for the same alloy system, and also the similar alloy systems studied by Cadirli and Gunduz, Kaya et al. (c) 2006 Elsevier B.V. All rights reserved.