peer-reviewed Background The Advanced Paramedic (AP) is a relatively recent role in Ireland and refers to a prehospital practitioner with Advanced Life Support (ALS) skills and training. The Advanced Paramedic Clinical Activity Study (APCAS) was initiated to provide an evaluation of the impact of the AP programme on patient care in Ireland. Aim The aim of this study is to provide an insight into the clinical activity of APs over a six month period in the Mid-West region of Ireland. Methods A prospective study was initiated whereby all ambulance calls dispatched by the regional Ambulance Control Centre were recorded by the attending AP, including calls received via the statutory 999/112 system. Participating APs were asked to complete a separate call log data sheet recording all demographic and clinical information for every call attended during the study period. Results A total of 17 APs participated and 1,969 ambulance calls were recorded in APCAS. The Mid-Western Regional Hospital, Limerick was the busiest receiving facility. Activity peaked at weekends and was lowest on Tuesdays. Crew response, on-scene and transport times agree with previous reports. Most common emergencies include Medical (12%), Cardiovascular (10%) and Altered level of Consciousness & Seizures (10%). Least common calls include Airway & Ventilation and Environmental emergencies (