Background: Late diagnosis results in delayed treatment, higher medical costs and an increased risk of mortality. However many HIV-infected patients in Africa are often diagnosed at very advanced stages of the disease. This study aims to narrow the information gap present in Ethiopia related to late testing.rnObjective: To identify factors involved with late presentation for HIV diagnosis within a free HIV program at public health facilities in south Wollo Zone.rnMethod: The study used quantitative study method in the form of facility based cross-sectional survey. The study was conducted at public health facilities which provide HIV care in south Wollo Zone from December 2010 to May 2011. According to single population proportion formula with an additional of 15% non-response rate, the total sample size was 437. To reach this amount of sample size within the data collection time, HIV diagnosed patients who were on ART care and had a CD4 cell count with in three months of their first HIV diagnosis were taken as study subjects. Data on socio-demographic, socio-economic, KAB towards HIV testing and HIV/AIDS, VCT factors, health system related and other factors were collected using pre-tested interviewer guided structured questionnaire. The collected data were entered using EPIINFO 3.5.1 and analyzed using SPSS 16. The impact of the variables on the likelihood of late testing was analyzed using binary logistic regression.rnResults: Of 437 subjects, 270 (61.8%) were defined as late testers. Males were twice as likely to present late as compared to females (p=0.005). Testing for health related reasons showed a significant positive association (p