Hyperbilirubinaemia with or without jaundice is one of the side effects of atazanavir boosted with low dose of ritonavir (ATV/rit) related to the drug plasma levels, as a result of its metabolism by UGT1A1 – ureidin-glucoronosyl-transferase. Genotyping for UGT1A1*28 before initiation of antiretroviral therapy containing atazanavir may aid in identifying individuals at risk of hyperbilirubinaemia. Our objective was to estimate the prevalence of UGTA1A1*28 polymorphism in HIV-infected individuals in Greece and to determine its potential association with hyperbilirubinaemia in patients receiving ATV/rit. The prevalence of the UGTA1A1*28 variant was estimated in 79 HIV-infected patients prior to the administration of the first-line treatment. The UGTA1A1*28 variant was detected in 46 out of 79 individuals (58.2%). Antiretroviral treatment was administered in 64/79 patients (81%). Among them, 26/64 (40.6%) received ATV/rit. Of the ATV/rit-treated patients, 14 were found to be carriers of the UGT1A1*28 variant (54%), whereas maximum serum bilirubin levels were significantly higher in the carrier population (4.71 vs. 2.69 mg/dL, p = 0.026). In 50% of the population, maximum value was recorded in the first month of follow-up. Although carriage of UGT1A1 is linked with the development of hyperbilirubinaemia, the implementation of a pharmacogenomic approach in clinical practice cannot yet be recommended as a standard of care.