The present study aimed to apply diversity indices to determine the seasonal distribution of epipelic diatom communities in the lower Zab River in Kirkuk Province. Four sites were chosen and subjected to study (Sadr River Bridge, Ashraya Village, Al-Shamit Village, Al-Shak Village), and the sampling was conducted from September 2023 to April 2024. Diatoms dominated the epipelon community; the seasonal distributions of epipelic diatoms were shown in the total numbers at the study sites. The results recorded the lowest rate of for both central and pinnate diatoms at site 2 in the spring were (218 × 10⁴/cm³) at site 2 in Spring and the highest rate (512 × 10⁴ /cm³) at site 1 in aAutumn. The dominancy of some epipelic diatomic species was recorded during the study period; these genera were Nitzschia, Navicula, Synedra, Cymbella, Gomphonema, Cocconies, Gyrosigma, Cyclotella, and Fragiaria. The diversity indices such as the rRichness index, Shannon diversity index, sSpecies evenness, and Simpson's diversity index were applied to illustrate the distribution of epipelic diatom community at the study sites. The data obtained would fill the gap in literature, providing adequate information on the topic addressed.