Small, dense low-density lipoprotein (sdLDL) and small-sized high-density lipoprotein (HDL) particles are established risk factors for ischemic heart disease. However, their clinical significance for acute ischemic stroke (AIS) is uncertain. This study evaluates associations of LDL and HDL particle sizes and subclasses with AIS risk and short-term mortality after AIS. Two hundred AIS patients hospitalised for first-in-a-lifetime stroke and 162 apparently healthy controls were included in the study. LDL and HDL particles were separated by gradient gel electrophoresis and serum lipid parameters were measured by standard laboratory methods. Baseline characteristics of LDL and HDL particles were evaluated for the prediction of AIS and short-term mortality after AIS. AIS patients had significantly more LDL III and IVb, but less LDL I and II particles. They also had significantly smaller HDL size, more HDL 3a, 3b and 3c and less HDL 2b subclasses. The relative content of both sdLDL and small-sized HDL particles was significantly increased in patients (P<0.001 and P<0.001, respectively). In addition, sdLDL was significantly higher in AIS fatalities (n=25) compared with survivors (n=175, P<0.05). Increased sdLDL was a significant predictor of AIS (OR=4.31; P<0.001) and in-hospital mortality after AIS (OR=5.50; P<0.05). The observed relationships persisted after adjustment for conventional risk factors. AIS is associated with adverse distributions of LDL and HDL subclasses. In addition, short-term mortality after AIS is associated with increased sdLDL particles. Our results indicate that sdLDL is an independent predictor of both AIS onset and consecutive short-term mortality. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.