Rheumatoid arthritis (RA) has been associated with a relative expansion of faecal Prevotellaceae. To determine the microbiome composition and prevalence of spp. in a group of individuals at increased risk for RA, but prior to the development of the disease. In an ongoing cohort study of first-degree relatives (FDRs) of patients with RA, we identified 'FDR controls', asymptomatic and without autoantibodies, and individuals in pre-clinical RA stages, who had either developed anticitrullinated peptide antibodies or rheumatoid factor positivity and/or symptoms and signs associated with possible RA. Stool sampling and culture-independent microbiota analyses were performed followed by descriptive statistics and statistical analyses of community structures. A total of 133 participants were included, of which 50 were categorised as 'FDR controls' and 83 in 'pre-clinical RA stages'. The microbiota of individuals in 'pre-clinical RA stages' was significantly altered compared with FDR controls. We found a significant enrichment of the bacterial family Prevotellaceae, particularly spp., in the 'pre-clinical RA' group (p=0.04). spp. enrichment in individuals in pre-clinical stages of RA, before the onset of RA, suggests a role of intestinal dysbiosis in the development of RA.