The aim of this study was to estimate the prevalence of serum antibodies to Actinobacillus pleuropneumoniae (APP) in Finnish farmed wild boars and to evaluate basic risk factors for seropositivity of the agent. A sampling frame was compiled based on the national record of wild boar farmers (n = 117), and 26 herds were included in the study. Serum samples (n = 206) were obtained from all animals slaughtered from these herds during the 2007–2008 period. Indirect enzyme-linked immunosorbent assay techniques were used to detect the possible presence of antibodies toward 12 serotypes of APP. Altogether, 1,442 analyses were performed, out of which 35 (2.4%) exceeded the positive cut-off value. Correspondingly, 26 of the pigs (12.6%) were found to be seropositive for any serotype of APP. The apparent animal prevalence of the cross-reacting APP serotypes 1, 9, and 11 was 3.9% (95% confidence interval [CI] 1–7%); it was 0.5% (CI 0–1%) for serotype 2; 3.4% (CI 1–6%) for serotypes 3, 6, and 8; 7.3% (CI 4–11%) for serotypes 4 and 7; 0.5% (CI 0–1%) for serotype 10; and 1.5% (CI 0–3%) for serotype 12. No antibodies against serotype 5s were detected. The apparent farm prevalence of APP serotypes 1, 9, and 11 was 15.4% (CI 2–29%); that of serotype 2 was 3.8% (CI 0–11%); that of serotypes 3, 6, and 8 was 11.5% (CI 0–24%); that of serotypes 4 and 7 was 34.6% (CI 16–53%); that of serotype 10 was 3.8% (CI 0–11%); and that of serotype 12 was 7.7% (CI 0–18%). In conclusion, the prevalence of serum antibodies to different APP serotypes was low in farmed wild boar. Risk factor analysis did not reveal any significant animal- or herd-level risk factors for seropositivity of the agent.