Four new cassane-type diterpenes, Neocaesalpin S (1), Neocaesalpin T (2), Neocaesalpin U (3), and Neocaesalpin V (4) were isolated from Caesalpinia minax HANCE together with seven known compounds Neocaesalpin A (5), Neocaesalpin K (6), Neocaesalpin L (7), Neocaesalpin M (8), Neocaesalpin O (9), Neocaesalpin MP (10), and Magnicaesalpin (11). Their structures were elucidated on the basis of 1D- and 2D-NMR, MS, and circular dichroism (CD) analysis. Compounds 1-4 were tested against liver cancer (HepG-2) and breast cancer (MCF-7), and showed mild antiproliferative activity.