Abstract: This study was conducted in ordered to analyze of phylogenetic relationships and determination of relationship amounts in all peanut cocoon strains of Islamic Republic of Iran germplasm based on reproductive characteristics. Hierarchical agglomerative clustering was done by using NTSYS-pc, version 2.02e based on complete, single, UPGMA, UPGMC, FLEXI approaches and SAS-pc based on WARD and average approaches. However, method of average linkage between groups under UPGMA (Unweighted Pair-Group Method using Arithmetic average) was considered as major and final protocol for data conclusion and the resulting clusters were expressed as dendrograms. Various methods generated similar dendograms. This study reveals the phylogenetic relationship of peanut cocoon strains of Iran germplasm. Based on data from studied characters, we constructed dendrograms that resolved the 51 silkworm strains into 2 major clusters. However, the strains of the same origin did not grouped together, demonstrating they can have different biological and development performance. First cluster divided into one sub-group included five strains. However, second cluster divided into two sub-groups. Other strains were grouped together and far from other silkworm strains, indicating they might be suitable for future crossings, maintenance of parental strains and hybridizations with oval cocoon strains so as to maximize heterosis and to avoid depression inbreeding.