Crohn's disease is characterized by a gut dysbiosis with decreased abundance of butyrate producers such as . Although secretes anti-inflammatory molecules, few studies have addressed the importance of in a longitudinal setting. We aimed to examine the relationship between temporal profiles of , the group, overall butyrate production, and inflammatory activity. Fecal samples ( = 59) were collected every third month from nine patients with ileal Crohn's disease. The abundance of and was quantified relative to the total amount of bacteria using quantitative-PCR. To assess butyrate production of gut microbiota, gene copy numbers of the butyryl-CoA:acetate-CoA transferase (BCoAT) gene were quantified by qPCR. The inflammatory activity was defined by fecal (f)-calprotectin. No correlation between the relative abundance of , the group, or copy numbers of the BCoAT gene, and f-calprotectin was observed in the total sample set. By analyzing alterations between consecutive samples, a negative correlation between changes in the relative abundance of and f-calprotectin was observed ( = -0.39;  = .009). Changes in ( = -0.18,  = .23) and number of copies of the BCoAT gene ( = -0.12;  = .42) did not correlate with f-calprotectin. There was an inverse correlation between temporal changes in the relative abundance of , but not overall butyrate producing capacity, and changes in inflammatory activity in ileal Crohn's disease. These findings indicate that may play a role in gut homeostasis, even though causality is still to be demonstrated.