In this study, the variability of essential oil composition in different parts of summer savory was investigated. Extraction of essential oils from air-dried leaves and healthy seeds was done using water-distillation in Clevenger-type apparatus for 4 h. In total, 23 and 24 components were identified in the leaves and seeds of summer savory, respectively. Carvacrol (46.023%), Estragole (Methyl Chavicol) (6.257%), Caryophyllene (4.753%), and E-Caryophyllene (4.753%) were the major constituents in the seeds and Carvacrol (56.537%), γ-Terpinene (21.377%), and p-Cymene (8.587%) were the major constituents in the leaves. Among all constituents, Carvacrol, Caryophyllene, E-Caryophyllene, β-Bisabolene, cis-α-Bisabolene, Caryophyllene oxide, Z-Citral, E-Citral, γ-Terpinene, and δ-3-Carene were present in both of leaves and seeds. Significant positive and negative correlations were detected between constituents for the investigated parts of summer savory. In addition, the correlation analysis of same volatile constituents in seeds and leaves indicated that some constituents in one part of summer savory have a significant correlation with another part. Also, γ-Terpinene in leaves has a negative significant correlation with γ-Terpinene in the seeds.