Primary HIV infection (PHI) is symptomatic in 50–90% of patients. The diagnosis, however, is seldom made at first presentation. This is probably because of the multifaceted and unspecific manifestations, the omission to perform adequate diagnostic testing and the failure to assess risks for PHI. Meningoencephalitis has been described as a fairly common presenting condition in PHI, with nuchal rigidity, fatigue, photophobia and headache; therefore, PHI should be considered in the differential diagnosis of aseptic meningitis. We present the case of a man with acute coma and a presumptive diagnosis of viral encephalitis in whom serological testing showed HIV encephalitis during PHI.