The morphological variation of Penaeus monodon was studied based on the morphometric analyses of samples collected throughout Banda Aceh, Khanom, Mozambique and Sanya. A total of 470 samples were investigated using eight measurements. Multivariate analyses [principal components (PCA), discriminant function (DFA) and cluster analyses (CA)] revealed obvious morphometric differences among the four geographical populations. PCA indicated that the first three components of the females and the first two components of the males accounted for 75.17% and 71.84% of the total morphological variability respectively. In DFA, the overall assignment of female and male individuals into their original population was 78.95% and 84.37% respectively. For females, the proportion of individuals correctly classified into their original population was 76.0%, 92.8%, 92.6% and 54.5% for population 1, 2, 3 and 4 respectively. For males, the proportion was 97.2%, 68.1%, 100% and 72.2% respectively. For females and males, CA showed that the four populations could be divided into two main clusters of morphological characteristics. CA also indicated that the morphological variation of population 3 was greater, whereas the morphology of population 2 was strikingly similar to that of population 4.