Background. HIV-infected injecting drug users (HIV-IDUs) are a major challenge to the Romanian healthcare system due to their high morbidity, mortality and health-care costs. Objective. The aim of this study was to determine the prevalence of late presenters (LP) among HIV-IDUs admitted to "Victor Babes" Clinical Hospital for Infectious Diseases, Bucharest and to evaluate their demographic and clinical characteristics. Methods. We performed a prospective study on HIV-IDUs diagnosed with severe immunosuppression, admitted between January 2009 and December 2014. HIV-IDUs with CD4 cell counts <350/mm(3) were considered LP and those with CD4 to a tertiary facility <200/mm(3) were defined with advanced HIV disease (AHD). These two groups were compared to a group of the HIV-IDUs that was diagnosed early in the evolution of illness (CD4 cell count >350/mm(3)). Statistical analysis was performed using SPSS v 20.0. Results. Out of 495 HIV-IDUs admitted during the study period, 238 (48.0%) were LP and 168 (33.7%) had AHD. The proportion of LP increased from 37.5% in 2009 to 52.6% in 2014 (0<0.001). Almost all HIV-IDUs, regardless of CD4 cell count, were young males (413, 83.4%), from urban areas (453, 91.5%), unemployed (393, 79.3%) and with low educational level (381, 76.9%). The median age at drug use initiation of 19 years (IQR 16-24) and the median duration of drug use at 9 years (IQR 4-13), were similar in both groups. More than half of all HIV-IDUs initially used intravenous heroin and afterwards legal highs (339, 68.4%) and (81, 16.3%) used only legal highs. The median CD4 cell count for the LPs was 104 cells/mm(3) (IQR 24-220) and the median HIV viral load 5.44 log10 copies/mL (IQR 5.00-6.00). Compared to early diagnosed HIV-IDUs (257), late presenters were more frequently diagnosed with opportunistic infections, especially tuberculosis (117, 49.1%) vs. (37, 14.3%), p<0.0001 and severe bacterial infections, mainly respiratory (54, 22.6%) vs. (46, 17.8%) p=0.02. Mortality was higher in LPs versus early presenters IDU (7, 2.7%) vs. (54, 22.6%) respectively p<0.0001. Conclusions. The proportion of LPs among HIV-IDUs diagnosed in our hospital increased alarmingly over the last few years. There were no significant differences regarding socio-demographic characteristics and drug use behaviour between late presenters and those diagnosed early, but LPs were more often diagnosed with opportunistic infections and had a significantly higher mortality rate.