The present study aimed to assess the genetic variation and phylogenetic relationships among six gastropod species using cytochrome c oxidase subunit 1 (CO1) sequences. The nucleotide lengths obtained from sequencing the mitochondrial CO1 gene varied from 633 to 658 bp. The partial CO1 sequences were submitted to GenBank with the following accession numbers: PQ216357.1 to PQ216362.1. The mean A+T content was 61.28%, exceeding the C+G content. Additionally, the mean content of pyrimidine (C+T) bases was 56.53%, which was higher than that of purines. Two approaches were used for phylogenetic reconstruction: Neighbor Joining and Minimum Evolution. Both methods indicated that the species of Neritimorpha were divided into two main clusters. One cluster contained four species: the understudied Nerita albicilla, Nerita sanguinolenta, as well as Nerita albicilla (EU253101.1) and Nerita sanguinolenta (EU732306.1) from GenBank/NCBI. The other cluster included the remaining species. Furthermore, the results demonstrated a close genetic relationship among the understudied Peronia verruculata and both Peronia verruculata (ON524819.1) and Peronia persiae (MK312167.1) from GenBank/NCBI. Additionally, the analyses revealed that Neritimorpha is a sister group to Heterobranchia.