BACKGROUND/OBJECTIVES: The gut microbiota contributes to energy acquisition from food, and changes in the gut microbiome are associated with obesity. The eating habits of Saudis are much different than those of Europeans, and our objective was to compare the fecal microbiota of obese and normal weight Saudis and French. SUBJECTS/METHODS: Illumina MiSeq deep sequencing was used to test the gut microbiota of 9 normal weight and 9 obese individuals from Saudi Arabia and 16 normal weight and 12 obese individuals from France. RESULTS: Obese French possessed significantly more relative Proteobacteria (P = 0.002) and Bacteroidetes (P = 0.05) and had lower richness and biodiversity at all the operational taxonomic unit (OTU) cutoffs (Po0.05) than normal weight French. Obese Saudis possessed significantly more Firmicutes (P = 0.001) without a difference in richness (P = 0.2) and biodiversity (P = 0.3) compared with normal weight Saudis. We found a common bacterial species core of 23 species existing in >= 50% of obese and normal weight Saudis and 29 species in. 50% of obese and normal weight French. Actinomyces odontolyticus, Escherichia coli and Ruminococcus obeum were present in at least 50% of all individuals tested. French individuals had significantly higher richness and biodiversity compared with Saudis at all the OTU cutoffs (P < 0.05). CONCLUSION: Microbiota differences between obese and normal weight French were not similar to those between obese and normal weight Saudis. The studies of different populations can result in contrasting data regarding the associations of the gut microbiota and obesity.