Purpose. It is assumed that osteosarcomas of the jaws mainly occur at older ages, whereas the most prominent sites, that is, the long bones, are more affected at ages <20. Jaw-localized tumors are less malignant and have lower metastatic spread rates. Patients and Methods. This study analyses the nationwide data of the Dutch Cancer Registry on osteosarcoma during the period from 1991 to 2010. Age-corrected incidence rates were calculated. Results. In 949, 38 patients had tumors in the maxilla and in 58 in the mandible. Median age for maxilla, mandible, and other localizations was 45.5, 49, and 23 years, respectively. Age-corrected incidence for osteosarcomas increased after a steep decline for the age cohorts from 20 to 60 years to nearly the same level as the younger patients. The incidence for maxillary lesions showed a steady increase from 0.46 to 1.60 per million over all age ranges; the highest incidence for mandibular lesions was found in the age cohort from 60 to 79 years. In respect to histology, no shifts for age were found, except for Paget's disease-related osteosarcoma. In older patients, chemotherapy was omitted more often. Overall survival was similar for all age groups, except for extragnatic tumor patients in the age range of 60-79 years. Conclusions. Osteosarcomas have comparable incidences below the age of 20 as compared with ages >60 years. Poorer outcome in older people is likely due to refraining from chemotherapy.