Epidemiological studies have linked high concentrations of airborne ultrafine particles with adverse cardiovascular effects, particularly in elderly subjects with existing cardiopulmonary compromise. Against this background, in the present study adult (6months) and geriatric SHR (13months) were either inhalation exposed to filtered air or UfCP (23nm; 5±10⁶cm^-3) for 24hrs in order to assess anticipated effects of UfCP inhalation on cardiac function. ECG and blood pressure were monitored telemetrically (n=28) over a 6day period covering baseline (day0), exposure (day1), and recovery period (days2–5). On day2, diastolic blood pressure (dBP) was elevated in exposed SHR compared with age matched controls, while heart rate (HR) was increased on day3 of the study protocol (linear mixed regression model; adult: p<.01, geriatric: p<.001). Overall, the observed transient elevations were more pronounced in geriatric SHR and the dBP elevation preceded the increase in HR. No associations between acute UfCP exposure and various inflammatory indices were observed in additionally exposed, non-equipped rats (n=28). Cardiac effects in compromised rats thus seem to be independent of inflammatory reactions suggesting altered cardiac autonomic function with a lag of 1day and 2days post exposure, respectively.