Tubulointerstitial nephritis (TIN) is not commonly associated in aminosalicylate-naïve patients with Crohn's disease (CD). Our case describes the initial presentation, diagnosis, and management of an adolescent presenting with TIN and underlying CD. Our case emphasizes that CD should be considered in the differential diagnosis of interstitial nephritis as not only a medication-related effect, but also as an extraintestinal manifestation of CD. We also describe successful management of undiagnosed recurring and symptomatic CD-related TIN with infliximab.