359 sibs from 92 families, where any one member of the family (basic unit of study) was found to be affected, were screened for myopia. Data on age at onset, parity and severity were studied in relation to consanguinity. Significant consanguinity differentials in the manifestation of myopia were seen. Offspring who were the product of a consanguineous mating manifested myopia more frequently as compared to the offspring from the non-consanguineous matings (control group). Males from consanguineous matings were affected in a higher frequency and manifested myopia at early ages. Myopia was found to be birth order-dependent. Pedigree analysis has shown that myopia is not a monogenic trait. The most plausible mode of inheritance of myopia seems to be polygenic with variable expressivity, and shows gene dosage effect.