Recently, exclusive loss of paternal 19q alleles in six of six oligodendrogliomas has been reported, indicating that parental imprinting plays a role in these tumors. We examined a series of 10 oligodendrogliomas and 3 oligoastrocytomas with allelic losses on 1p and 19q for the parental origin of the lost alleles. Ten cases lost paternal 1p alleles and 3 cases lost maternal alleles. For 19q, six cases had loss of paternal alleles and seven cases of had loss of maternal alleles. These random distributions do not support the hypothesis that parental imprinting accounts for inactivation of the putative oligodendroglioma tumor suppressor genes.