The study analyzes the sexual contact network of a random sample of 4781 Swedish individuals, revealing a scale-free structure. The cumulative distribution of the number of sexual partners over the past year follows a power law with exponents α ≈ 2.4 for both males and females, indicating a scale-free network. This structure suggests that strategic interventions targeting high-risk individuals could be effective in preventing sexually transmitted diseases. The network's scale-free nature implies that the concept of a "core group" in epidemiology is arbitrary, as there is no clear boundary between core and non-core individuals. The study also shows that scale-free networks are more susceptible to disease spread than single-scale networks, and that targeting high-connectivity nodes could be more effective in controlling epidemics. The findings have implications for public health strategies, emphasizing the importance of focusing on individuals with many sexual partners. The data were collected from a 1996 survey with a 59% response rate, and the sample is representative except for an under-representation of elderly individuals. The results contrast with exponential or Gaussian distributions, suggesting mechanisms such as increased skill in acquiring partners or attractiveness may explain the observed structure. The study highlights the importance of understanding network structures in public health and disease control.The study analyzes the sexual contact network of a random sample of 4781 Swedish individuals, revealing a scale-free structure. The cumulative distribution of the number of sexual partners over the past year follows a power law with exponents α ≈ 2.4 for both males and females, indicating a scale-free network. This structure suggests that strategic interventions targeting high-risk individuals could be effective in preventing sexually transmitted diseases. The network's scale-free nature implies that the concept of a "core group" in epidemiology is arbitrary, as there is no clear boundary between core and non-core individuals. The study also shows that scale-free networks are more susceptible to disease spread than single-scale networks, and that targeting high-connectivity nodes could be more effective in controlling epidemics. The findings have implications for public health strategies, emphasizing the importance of focusing on individuals with many sexual partners. The data were collected from a 1996 survey with a 59% response rate, and the sample is representative except for an under-representation of elderly individuals. The results contrast with exponential or Gaussian distributions, suggesting mechanisms such as increased skill in acquiring partners or attractiveness may explain the observed structure. The study highlights the importance of understanding network structures in public health and disease control.