Background: There have been few studies in Turkey on the incidence of childhood cancers. A mother's knowledge about signs and symptoms of cancer is important for early diagnosis, effective treatment, and improvement of life expectancy. This study was conducted with a group of mothers of children, aged 0-13, at a Family Health Center (FHC) in Turkey's Eastern Black Sea Region, to analyze their knowledge about cancer symptoms in childhood. Materials and Methods: The study group of this descriptive/cross-sectional research comprised 2,061 mothers, ages 19-49, at an FHC in the Eastern Black Sea Region in February 1, 2011 - June 1, 2011. Before the study, permission was obtained from the local ethics board and the institutions concerned. A value of p<0.05 was accepted as statistically significant. Results: Of the mothers, 34.9% were between the ages of 40-47, 40.5% had three children, 73.8% had no experience with children with cancer, 45.9% said they learned about cancer on television, 39.7% stated that the primary reason for childhood cancer was the mother's smoking during pregnancy, 68.8% said that early diagnosis would save a child, and 98% wanted to learn about childhood cancer. Conclusion: It was determined that the mothers' knowledge of cancer was deficient.