Human respiratory syncytial virus (hRSV) is recognized as the most important viral agent of serious respiratory tract diseases in the pediatric population worldwide. A prospective study for hRSV was conducted in children ageing less than 1 year admitted in two university hospitals in Campinas, São Paulo, Brazil. The aim of the present study was to investigate the genetic variability of both A and B subgroups of hRSV isolated during an epidemic period in the Campinas metropolitan region, Brazil, by sequencing a variable region of the G protein gene. Phylogenetic trees were constructed from alignments of sequences available in the GenBank database and Brazil isolates for hRSV A and B. The data demonstrate that Brazilian isolates clusters together with A and B viruses from Kenya, New Zealand, South Africa, West Virginia, United States (CH, Rochester), and other Brazilian isolates. Phylogenetic analysis of subgroup A isolates showed that the sequences obtained on the present study falls on three clusters, namely GA2, GA5, and SAA1 that co-circulate during the analyzed period. Subgroup B isolates detected belongs to three genotypes, GB3 (SAB3) and BA (BAIII). Different subgroup B genotypes were detected and BA isolates present in our samples showed some degree of genetic variability. This is one of the first reports on the molecular epidemiology of hRSV strains from the Campinas metropolitan region, São Paulo state, Brazil. And is also the first description of the circulation pattern of hRSV genotypes in two university hospitals, revealing interesting differences between the two subgroups of the virus.