RESUMO
Background: Non metric cranial variants have always been a topic of considerable interest for research workers, as they possess racial, regional and sex dimorphic differences. These variants are also of anthropometric, genetic, morphological and forensic importance. Material and methods: 71 skulls from north indian region were studied for one of such variant, absence of mastoid foramen and presence of multiple mastoid foramen. Results: Incidence of absent mastoid foramen is 7.04 %, while bilateral incidence of absent mastoid foramen is only 1.4 %, however unilaterally mastoid foramen is absent in 5.63 %. (2.8 % on right side and 2.8 % on left side). Incidence of multiple mastoid foramina is 12.67 %, out of this it is bilateral in 8.45 %, however unilaterally it is present in 4.22 %. ( 1.40 % on right side and 2.81 % on left side).Conclusions: Findings are discussed and compared with other global studies and are found to be of considerable racial and regional significance. Knowledge of this variant is valuable in some neurosurgical and otolaryngeal procedures.