Pneumonia leads to considerable morbidity and mortality in nursing home residents with dementia. We assessed pneumonia incidence based on data from three different studies: (1) real-time national surveillance of healthcare-associated infections in nursing home residents in 2009–2015; (2) a randomized controlled trial in 2012–2015 to assess effects of a practical guideline in nursing home residents with dementia and pneumonia; and (3) a study in 2007–2010 to assess quality of dying in newly admitted nursing home residents with dementia. In national surveillance data, pneumonia incidence was calculated separately for psychogeriatric and somatic beds, as a proxy for residents with and without dementia. Weekly pneumonia incidence was significantly lower per 1000 psychogeriatric beds (3·9; 95% confidence interval (CI) 3·2–4·6) compared with 1000 somatic beds (5·7; 95% CI 5·1–6·3). Annual incidence per 1000 psychogeriatric beds was similar in national surveillance (range 78·9–117·1) and the trial (range 71·0–94·3), and significantly higher in newly admitted dementia residents (range 267·3–363·2). The incidence was highest during the first months after admission when compared with residents with longer stay. In conclusion, follow-up of pneumonia in newly admitted dementia residents may result in higher incidence, possibly due to higher risk in this population.