Anaplasma platys is a Gram-negative bacterium that can infect platelets. It is transmitted by ticks and is one of the Companion Vector-Borne Disease (CVBD) which has a considerable impact on dogs throughout the world. Information on this disease is very limited in Indonesia. The symptoms are not specific, so it requires molecular analysis as a rapid and accurate diagnostic. GroEL is an essential gene which is commonly used for classification and species identification of bacteria, including Anaplasma spp. The aim of this study was to conduct molecular diagnosis of anaplasmosis based on the groEL gene sequence using the polymerase chain reaction (PCR) method. This study was also intended to study the genetic diversity of Anaplasma platys species in infected dog patients from Yogyakarta area, Indonesia. The blood samples were collected from 51 dogs suspected anaplasmosis in Prof. Dr. Soeparwi Animal Hospital, animal clinics, and pet shops in Yogyakarta area based on anamnesis, history of tick infestations, and clinical symptom examinations. DNA extracted from blood samples were subjected to PCR targeting on  groEL  gene and then were sequenced. The phylogenetic tree analysis and construction were carried out by using Basic Local Alignment Search Tool (BLAST) and Molecular Evolutionary Genetics Analysis (MEGA) version 7.0. Positive sample results of PCR (amplicon length 624 bp) were found in 6 of 51 dogs examined. Samples A1 (KHJ/C2), A2 (KHJ/A2), A3 (KSK/L), A4 (KHJ/L), and A5 (KNP/M2) indicated close ties to Anaplasma platys (AF478129.1). Phylogenetic analysis showed a very high homology with a bootstrap value of 100%. It can be concluded that there is no genetic diversity of Anaplasma platys which infected dogs in Yogyakarta area, Indonesia.