Background To improve HIV detection, Royal Darwin Hospital implemented a guideline in 2012 recommending routine HIV testing for all adult acute medical admissions. This study aimed to determine the uptake, point prevalence and impact on late diagnosis of HIV screening following guideline implementation. Methods: Data on the number of HIV tests and number of acute medical admissions over the 8 months prior and post guideline implementation were extracted from hospital databases. A qualitative survey was conducted to ascertain clinician response to routine screening. Results: Fourteen per cent of admissions were tested post-implementation compared with 5.3% during the implementation period (P < 0.001). HIV prevalence pre-implementation was 1.4% compared with 0.3% following implementation (P < 0.05). The average CD4 count at diagnosis was <200 cells/mm3. Conclusions: There was a significant increase in HIV testing following guideline implementation; however, the overall testing rate remained low. Routine screening did not increase detection of HIV, and HIV continues to be diagnosed late at Royal Darwin Hospital. Methods for improving understanding of the rationale for routine screening and increased promotion of the guidelines are required to increase testing.