Biochemical and cytologic testing, bacterial cultures, and PCR of pericardial fluid samples for cytomegalovirus, varicella zoster and herpes simplex viruses, parvovirus B19, fungal 18S rRNA, bacterial 16S rRNA, and Mycobacterium tuberculosis were negative. She had thrombocytopenia, a leukocyte count within the normal range, and a high C-reactive protein level. The patient, a 14-year-old girl who had thoracic scoliosis surgery in 2007, was admitted to the hospital in 2009 for pleuropneumonia and pericarditis, which required pericardial drainage twice within 3 weeks (samples PF 1 and PF 2, respectively). We report the presence of 2 divergent GcVs and a novel CRESS-DNA virus (CV) in 2 pericardial fluid samples from a patient with idiopathic recurrent pericarditis. GcVs have also been found in the brain and serum of humans with multiple sclerosis in the cerebrospinal fluid of a patient with encephalitis and in several blood samples, including those from an HIV-positive blood donor ( 6– 8). Gemycircularvirus (GcV) were initially discovered in fungi, but a growing number of new species has been characterized by metagenomics in air, sewage, insects, and feces from a broad range of vertebrates ( 1– 5). To the Editor: Circular replication initiation protein (Rep)–encoding single-stranded DNA (ssDNA) (CRESS-DNA) genomes are found in diverse group II virus families, which all possess a conserved Rep-encoding gene and a nonenveloped icosahedral capsid, except geminiviruses, which have twinned particles ( 1).