We explored the relationship between socio-economic characteristics and cancer stage at presentation. Patients admitted to a university hospital for diagnosis and treatment of cancer provided data on their education, vocational training, income, employment, job, health insurance and postcode. Tumor stage was classified according to the Union International Contre le Cancer (UICC). To analyze disparities in the likelihood of late-stage (UICC III/IV vs. I/II) diagnoses, logistic regression models adjusting for age and gender were used. Out of 1,012 patients, 572 (59%) had late-stage cancer. Separately tested, increased odds of advanced disease were associated with post-compulsory education compared to college degrees, with apprenticeship and no vocational training, with unemployment, disability pension, jobs with a low hierarchy level, blue collar jobs and with low income. Health insurance and community size were not related with late-stage cancer. Jointly modelled, there was evidence for an independent effect of unemployment (odds ratio (OR) 1.7, CI 1.0–2.8), disability pension (OR 1.8, CI 1.0–3.2) and very low income (OR 2.6, CI 1.1–6.1) on the likelihood of advanced disease stage. It is of great concern that these socio-economic gradients occur even in systems with equal access to health care.