Rotavirus is the most common agent of acute gastroenteritis in children under five years of age and still a major cause of mortality and morbidity mainly in devoloping countries. The aim of this study was to determine the circulating rotavirus genotypes in children less than five years of age with acute gastroenteritis in Adana province, before the introduction of the rotavirus vaccine into the national immunization programme. Fecal specimens were collected from children enrolled between December 2012 and November 2016 and rotavirus antigen was searched by a rapid immunochromatographic test method. The antigen positive samples were G and Pgenotyped by hemi-nested type-specific multiplex reverse-transcriptase polymerase chain reaction (RT-PCR). Rotavirus antigen positive fecal specimens from 201 patients of 107 (53.3%) boys and 94 (46.8%) girls were included in this study. Rotavirus infection was most frequently detected in patients with gastroenteritis between the ages of 12 and 23 months. It has been determined that 45% of rotavirus gastroenteritis was determined in children under two years of age. Rotavirus gastroenteritis was more frequent between September and April, but the highest incidence was detected in January. Of 201 rotavirus antigen-positive stool specimens, 167 were PCR positive. Five common G (G1, G2, G3, G4 and G9) and two common P genotypes (P and P) were determined as 91.6% and 96.4% of the isolates, respectively. The most prevalent G and P genotype combination was G1 P8 with a frequency of 29.9%, followed by 21% G9P8 About 78% of rotavirus isolates were classified into five common G-P combination genotypes, including G1P8, G9P8 G3P8, G2P4, and G2P8. During the study period, there were significant changes in the distribution of rotavirus genotype. The prevalence of G9P8 genotype sharply decreased from 40% to 8.1% and the prevalence of G1P8 genotype increased from 21.3% to 48.6%. Although no G3P8 isolates were detected in the first two years of the study, this genotype was detected in 18.5% and 13.5% of the samples in 2015 and 2016, respectively. There were no relationship between the age onset of the disease, sex, dehydration development risk and rotavirus genotype. The results from this study indicated that the predominant circulating strains of rotavirus determined in clinical specimens were G1P8 and G9P8. Significant changes were observed in the prevalence of the most common rotavirus isolates over the years. Rotavirus surveillance is important to determine the circulating strains of rotavirus to assess vaccine effectiveness, to monitor vaccine failures, and to detect potential emerging strains.