The aim of this study is to assess the impact of a broad range of possible factors relating to work, personal circumstances and attitudes towards sickness absence on a person's decision to go to work despite feeling ill, a phenomenon that has been termed sickness presence (SP), or 'presenteeism', in the literature. Using data from a random sample of 12,935 members from the core Danish work force the hypotheses were tested in a cross-sectional design utilising ordered logistic regression models. The results indicate that more than 70% of the core work force goes ill to work at least once during a 12-month period. This means that SP is just as prevalent a phenomenon as sickness absence. Many of the results from earlier studies of SP were replicated and new factors were discovered: for example time pressure (having a supervisory role and/or working more than 45 h per week) and relationship with colleagues (measured by working in a small company, having non-standard hours and degree of cooperation) both increase the likelihood of SP. However, personal circumstances and attitudes, e.g. treating work as home (cf. Hochschild's thesis) and being over-committed to work, were also found to lead to higher levels of SP. Finally, we found that those with a conservative attitude to absence were most likely to turn up ill at work. Overall, work-related factors seem to be slightly more important than personal circumstances or attitudes in determining people's 'decision' to go ill at work. However, the relatively low explanatory power of these combined factors suggests that there are still many unknowns in this field of research.