A chlorophyll deficiency expressed as yellowing of leaves was observed in hazelnut (Corylus avellana L.) progenies. Segregation ratios approximated 3 green: 1 yellow, indicating control by a single recessive gene designated chlorophyll deficient #1, for which the symbol c, is proposed. `Barcelona', `Butler', `Compton', `Lansing', Willamette', and the ornamental selection `Redleaf #3' are heterozygous. Pedigree analysis strongly suggests that all heteroxygotes inherited the recessive allele from `Barcelona'. A cross of `Barcelona' with the yellow-leafed ornamental Corylus avellana L. var. aurea Kirchn. produced no yellow-leafed seedlings, indicating that the chlorophyll deficiencies from these two sources are controlled by different loci. Progenies segregating simultaneously for this trait and the gene controlling presence of anthocyanin indicated that the two traits are inherited independently. Seedlings deficient in chlorophyll but with anthocyanin were able to survive under field conditions, while leaves of yellow-leafed seedlings lacking anthocyanin became scorched and the trees died.