We report the evidence base that supported the decision to implement the first campus-wide hospital smoking ban in the Republic of Ireland with effect from 1 January 2009. Three separate data sources are utilized; surveillance data collected from patients and staff in 8 surveys between 1997 and 2006, a 1-week observational study to assess smoker behaviour in designated smoking shelters and an attitudinal interview with 28 smoker patients and 30 staff on the implications of the 2004 indoors workplace smoking ban, conducted in 2005. The main outcome measures were trends in prevalence of smoking over time according to age, sex and occupational groups and attitudes to the 2004 ban and a projected outright campus ban. Smoking rates among patients remained steady, 24.2% in 1997/98 and 22.7% in 2006. Staff smoking rates declined from 27.4% to 17.8%, with a strong occupational gradient. Observational evidence suggested a majority of those using smoking shelters in 2005 were women and health-care workers rather than patients. Attitudes of patients and staff were positive towards the 2004 ban, but with some ambivalence on the effectiveness of current arrangements. Staff particularly were concerned with patient safety issues associated with smoking outdoors. The 2004 ban was supported by 87.6% of patients and 81.3% of staff in 2006 and a majority of 58.6% of patients and 52.4% of staff agreed with an outright campus ban being implemented. These findings were persuasive in instigating a process in 2007/08 to go totally smoke-free by 2009, the stages for which are discussed.