OBJECTIVE: To describe the treatment outcomes of patients receiving dolutegravir (DTG) in a 'real-world setting' in Belgium. DESIGN: Retrospective, observational, multicenter cohort. METHODS: Inclusion criteria: HIV-1 patients at least 18 years old having received DTG as part of their combined antiretroviral therapy (cART) between 1 April 2014 and 1 December 2017. Primary endpoint: rate of virologic suppression, defined as plasma HIV-1 viral load less than 50 copies/ml, at weeks 24, 48, and 96. Secondary endpoints: durability, expressed as probability of experiencing loss of virologic suppression by week 96 (defined as two consecutive HIV-1 viral load measurements of at least 200 copies/ml after having initially achieved virologic suppression); immunological response at weeks 24, 48, and 96; incidence of and reasons for DTG discontinuation; and change in weight at week 96. RESULTS: Four thousand, one hundred and one patients were included. Through 96 weeks, virologic suppression rate was 96% (on-treatment analysis), probability of experiencing loss of virologic suppression was 7%, and mean increase in CD4 cell count was 100 cells/μl (SD 220). There were 785 (19.1%) discontinuations of DTG (8.9 discontinuations per 100 patient-years). The most common cause of discontinuation was an adverse drug reaction (ADR; 9.5%) with neuropsychiatric toxicity being the most prevalent (5.2%; 2.4 discontinuations per 100 patient-years). By week 96, the median change in weight for the study population was +2.0 kg (IQR -1 to 5). CONCLUSION: In this large cohort, DTG showed excellent virologic efficacy and was generally well tolerated. Whether DTG results in undesirable weight gain or rather statistically significant results, remains a debate.