The evaluation of potential environmental impacts from polycyclic aromatic hydrocarbon is a subject that requires investigation, especially related to emission sources from highway roads with high traffic. In this paper, the distribution of polycyclic aromatic hydrocarbons was investigated in the surface sediments from a subtropical lake, located in the south of Brazil and away from urban areas. The results showed that all sediments presented such compounds in significant concentration, ranging from 9.50 to 29.88 μg/g. The highest total concentration was found in those sites close to the highway (bridges) and the deepest area of the lake. Moreover, a high concentration of polycyclic aromatic hydrocarbons of high molecular weight, such as benzo(a)anthracene and dibenzo(a,h)anthracene was found. It was laso found that high concentrations might be related to asphalt and coal tar pavement used in the highway construction close to the lake. In addition, the potential capacity of sediment toxicity was compared with values of the interim sediment quality guidelines values. The results indicate that most of the sediment presents concentrations of hydrocarbons above these limits. Only fluoranthene and chrysene were found in concentrations below the guideline values. The concentrations of most of the polycyclic hydrocarbons are higher than the quality guidelines. However, the main concern is associated with the presence of benzo(a)anthracene whose concentration is 416 times higher than the limit establisehed by guidelines. The same observation can be done to traces of benzo(a)pyrene and dibenz(a,h)anthracene, with concentration values of 13 and 1,993 times higher.