Helminth infections are highly prevalent in tropical and subtropical countries, coexisting in Chagas disease endemic areas. Helminth infections in humans may modulate the host immune system, changing the Th1/Th2 polarization. This immunological disturbance could modify the immune response to other infections. The aim of this study is to evaluate the relationship between clinical, microbiological and epidemiological characteristics of Chagas disease patients, with the presence of helminth infection. A prospective observational study was conducted at Vall d'Hebron University Hospital (Barcelona, Spain). Inclusion criteria were: age over 18 years, diagnosis of Chagas disease, and not having received specific treatment for Chagas disease previously to the inclusion. The study protocol included Chagas disease assessment (cardiac and digestive evaluation, detection of T. cruzi DNA measured by PCR in peripheral blood), and helminth infection diagnosis (detection of IgG anti- Strongyloides stercoralis by ELISA, microscopic examination of stool samples from three different days, and specific faecal culture for S. stercoralis larvae). Overall, 65 patients were included, median age was 38 years, 75.4% were women and most of them came from Bolivia. Cardiac and digestive involvement was present in 18.5% and 27.7% of patients respectively. T. cruzi PCR was positive in 28 (43.1%) patients. Helminth infection was diagnosed in 12 (18.5%) patients. No differences were observed in clinical and epidemiological characteristics between patients with and without helminth infection. Nevertheless, the proportion of patients with positive T. cruzi PCR was higher among patients with helminth infection compared with patients without helminth infection (75% vs 35.8%, p = 0.021). We observed a high prevalence of S. stercoralis infection among chronic Chagas disease patients attended in our tropical medicine unit. Strongyloidiasis was associated with significantly higher proportion of positive T. cruzi RT-PCR determined in peripheral blood. Helminth infections (viz. Strongyloides stercoralis, hookworms, Ascaris lumbricoides, Trichuris trichiura) are highly prevalent in tropical and subtropical areas, and some of these infections may persist in the human host for many years after leaving the endemic area. It is known that helminth infection in humans may modulate the host immune system. This immunological disturbance could modify the immune response to other infections or the antibody production after vaccination. We prospectively studied a group of patients with chronic Chagas disease, with the aim of evaluate the impact of helminth co-infection in the clinical manifestations and microbiological features of Chagas disease. We observed a high prevalence of helminth infection (mostly due to S. stercoralis infection) among chronic Chagas disease patients attended in our tropical medicine unit. Strongyloidiasis was associated with significantly higher proportion of positive T. cruzi RT-PCR determined in peripheral blood. These data increase the scarce available information to understand the role of PCR techniques in the management of Chagas disease patients. Further studies are needed to deepen and confirm this interesting relationship