During one-year follow-up, plasma lipoprotein (Lp), and apolipoprotein (apo) spectra were studied in 119 patients with unstable angina (UA). Total lipids, cholesterol, various Lps, and apolipoproteins (apo B and apo AI) were examined in the plasma. The patients with UA showed more profound shifts in the spectrum of plasma apolipoproteins. In the patients, high density lipoprotein cholesterol levels below 37-38 mg/dl and an apo B/apo AI ratio over 1.7-1.9 were found to be a sign of high risk for myocardial infarction. It was ascertained that a relationship existed between the clinical course of the disease and changes in the plasma Lp and apolipoprotein spectra in the patients who failed to develop myocardial infarction over the one-year follow-up. During a year, increased "atherogenic" changes in the spectrum of Lp, apo were revealed in patients with a more severe clinical course of the disease as compared to an "instability" period; when the disease proceeded favourably, a "positive" time-course of these parameters was observed.