The complete nucleotide sequences of gene 9 (VP7) of rotavirus strains MGH66 and RHIB55 isolated in northern and southern Nigeria, respectively, were determined. The sequence of either strain was 1062 nucleotides along with two potential glycosylation sites and two in-phase initiation codons encoding a protein of 326 amino acids provided the first ATG codon was utilised. Comparison of the deduced amino acid sequences of VP7 of the strains with that of published sequences of serotype G1 strains and a representative strain of each of serotypes 2-6 and 8-14 revealed > or = 91.41% and > or = 81.60% homology, respectively. The stool sample obtained from a diarrhoeic child in Maiduguri containing strain MGH66 was classified by polymerase chain reaction (PCR) technique as possessing a dual infection specificity of VP7 serotypes G1 and G3. The nucleotide sequencing, however, revealed the dual infection specificity of VP7 serotypes G1 and G8. The implications of nucleotide sequence analysis for serotyping of rotavirus strains originating from different geographical regions and for vaccine development are discussed.