Objectives: To describe the presence and time-related pattern of circulating pregnancy associated plasma protein A (PAPP-A) levels in patients with non ST-segment elevation acute coronary syndrome (NSTE-ACS). Design and methods: Consecutively admitted patients (N = 573) with clinical signs of NSTE-ACS were included. Blood samples for analysis of PAPP-A were drawn at admission and every 6-8 h until levels of biomarkers of myocardial necrosis showed a consistent decrease. Results: High-risk NSTE-ACS was diagnosed in 123 patients (23%). Significantly more patients with high-risk NSTE-ACS (63%) had detectable PAPP-A than did those with low-risk NSTE-ACS (49%) (P < 0.001). PAPP-A concentrations were significantly associated with typical angina at admission, significant ST-depressions on the ECG, multivessel disease and presence of high-risk NSTE-ACS. Conclusion: PAPP-A seems to be a marker ischaemia both in patients with low- and high-risk NSTE-ACS, possibly due to the release of PAPP-A from the vulnerable plaque.