Purpose: The aim of this study was to measure patterns of complementary and alternative medicine (CAM) use among Finnish children and to explore whether CAM use among children is mainly complementary or alternative. Methods: We carried out a cross-sectional population-based survey in spring 2007. The study population consisted of a representative sample (n = 6000) of Finnish children under 12 years of age. A questionnaire was sent to their parents, and 4032 questionnaires were returned (response rate 67%). Pearson’s chi-squared test and logistic regression analysis were conducted to measure factors associated with CAM use. Results: The prevalence of CAM use among children was 11%. Fish oils and fatty acids (6%) followed by probiotics (4%) were the most commonly reported CAMs used. Being the first born, using vitamins and having at least one symptom predicted the use of CAMs. Parental use of vitamins and CAMs were also associated with CAM use among children. In the preceding 2 days, 3% of children in the study had used only CAMs, and 7% had used a CAM concomitantly with prescribed and/or over-the-counter medicines. Conclusions: Our results indicate that the use of CAMs among Finnish children is mainly for improving health and alleviating symptoms, especially in families where at least one parent also uses these modalities. CAMs were mainly used as complementary rather than as an alternative to conventional care. Healthcare professionals should be aware of this complementary use of CAMs and medicines in patients to avoid risks of potential interactions.