The study objectives were to evaluate the prevalence, predictors, and implications of pornographic Internet site (PIS) use among Greek adolescents. A cross-sectional study was conducted among 529 randomly selected Greek high school students. The prevalence of overall PIS use was 19.47% (n = 96). Among PIS users, 55 (57.29%) reported infrequent and 41 (42.71%) reported frequent PIS use. The predictors of infrequent PIS use included male gender (adjusted odds ratio [AOR] = 8.33; 95% confidence interval [CI] = 3.52-19.61), Internet use for sexual education (AOR = 5.26; 95% CI = 1.78-15.55), chat rooms (AOR = 2.95; 95% CI = 1.48-5.91), and purchases (AOR = 3.06; 95% CI = 1.22-7.67). The predictors of frequent PIS use were male gender (AOR = 19.61; 95% CI = 4.46-83.33), Internet use for sexual education (AOR = 7.39; 95% CI = 2.37-23.00), and less than 10 hours per week Internet use (AOR = 1.32; 95% CI = 1.10-1.59). Compared to non-PIS users, infrequent PIS users were twice as likely to have abnormal conduct problems (odds ratio [OR] = 2.74; 95% CI = 1.19-6.28); frequent PIS users were significantly more likely to have abnormal conduct problems (OR = 4.05; 95% CI = 1.57-10.46) and borderline prosocial score (OR = 4.22; 95% CI = 1.64-10.85). Thus, both infrequent and frequent PIS use are prevalent and significantly associated with social maladjustment among Greek adolescents.