This investigation aimed to evaluate the chemical constituents of rosemary (Rosmarinus officinalis L.) leaves and black cumin (Nigella sativa L.) seeds using different chemical analysis methods including moisture, ash, lipid, crude protein, total carbohydrates, crude fiber, total phenols, and essential oil as well as identify the dominant components of essential oils by using GC-MS. The results indicated that the proximate analysis of rosemary leaves achieved significantly the highest values of ash, crude fiber, total phenols, and essential oil, whereas black cumin seeds attained significantly the highest values of moisture, lipid, crude protein, and total carbohydrates. The essential oil content of rosemary leaves and black cumin seeds (1.04 and 0.39%, respectively) was significantly (p<0.05) different. Twenty essential oil components of rosemary leaves were identified. The main components of rosemary essential oil were α-pinene (17.13%) and 1.8 cineole (13.69%). On the other hand, eighteen essential oil components of black cumin seeds were identified. The predominant components of black cumin essential oil were Thymoquinone (38.43%) and P-cymene (21.18%).