Introduction The prevalence of diseases has been changing in Brazil in the last decades. The objective of this research was to estimate the prevalence of chronic diseases and health complaints among adolescents according to socioeconomic and demographic variables.

Method A cross-sectional population based survey was carried out in Campinas in the years 2008/09 (ISACamp 2008/09). Data of 929 adolescents from 10 to 19 years were obtained through household interviews. The analysis included prevalence ratio (PR) and 95% CI. Poisson regression was used for adjusted analysis.

Results 17.54% (CI 14.34 to 21.28) informed having one chronic disease and 1.62% (0.92 to 2.83) having more than one. Regarding health complaints 38.47% (31.98 to 45.39) referred not having any problem, 33.75% (29.55 to 38.21) informed one problem, 17.31% (15.46 to 20.58) two, 7.23% (5.27 to 9.83) three and 3.23% (1.88 to 5.56) four or more. Among the chronic diseases, asthma showed the higher prevalence: 7.59% (6.01 to 9.54). The most prevalent health complaints were: allergy 40.39% (34.90 to 46.13), frequent headache/migraine 24.83% (20.35 to 29.92), backache/column problems 11.84% (8.97 to 15.48) and emotional problems (anxiety and sadness) 10.65% (7.69 to 14.56). After adjusting for confounding the PR for chronic diseases were: 1.4 (1.06 to 1.82) for age over 15, 0.68 (0.46 to 0.99) for those still attending school, and 1.8 (1.06 to 3.18) for having children. The PR for health complaints were: 1.12 (1.01 to 1.24) for girls and 1.34 (1.11 to 1.62) for higher family income.

Conclusion Age from 15 to 19 years, not attending school and having children are associated with chronic diseases, and female adolescent and having a family income of over 4 minimum wages are associated with health complaints.