Introduction. Arboviruses, such as dengue and chikungunya, have caused multiple epidemics in the Americas. They are transmitted through mosquito bites; Aedes aegypti is their main vector. As of January 2023, coinciding with the fourth dengue outbreak in Argentina, a new dengue outbreak was observed in the Americas, coincident with the presence of chikungunya. We considered it essential to describe the demographic, epidemiological, clinical, and evolutionary characteristics of dengue/chikungunya patients seen in a tertiary pediatric hospital in the Autonomous City of Buenos Aires in 2023. Population and methods. Descriptive, observational, retrospective cohort study. Includes children of 0 to 16 years with compatible symptomatology and positive PCR or IgM for dengue or chikungunya from February 1, 2023, through May 31, 2023. Results. A total of 168 patients were identified, with a median age of 138 months (IQR: 107-164). The diagnosis of dengue was confirmed in 140 and of chikungunya in 28. Ninety-eight percent were autochthonous cases. In 85% of the cases, PCR was used to make the virological diagnosis of dengue, and in the remaining 15%, IgM was used. PCR diagnosed chikungunya in 61% of cases. Patients with dengue fever had a longer duration of fever, abdominal pain, headache, myalgias, and retroocular pain. Exanthema and arthralgias were associated with chikungunya. Conclusions . The epidemiology of mosquito-borne diseases is dynamic and is related to what happens in the rest of the countries of South America; knowledge of it is essential to predict the etiological risk and prevalence.