Purpose : Myopia is considered to be a complex disease involving both environmental and genetic factors. The Genes in Myopia (GEM) Study aims to recruit probands with myopia and their family members to allow genetic analysis of myopia to be undertaken. The purpose of this paper is to describe the methodology and recruitment of probands and families for the GEM Study. Methods : In a sample-based prospective study, 2,095 probands with myopia of -0.50 DS or worse and a positive family history of myopia were contacted via the Melbourne Excimer Laser Group (MELG) database. Probands and family members recruited into the study undertook a detailed assessment including questionnaire, best-corrected visual acuity, objective and subjective refraction, axial length, anterior chamber depth, keratometry readings, slit-lamp examination, height, weight and head circumference measurements, and blood sample collection for DNA analysis. Results : 280 probands with myopia have been recruited into the GEM Study. Probands had a mean age of 49.33 yrs. (SD +/- 11.64) with the average age of myopia onset being 12.58 years (SD +/- 6.71). The average spherical-component refractive error was: right eye -5.13 DS (SD +/- 3.06) and left eye -5.14 DS (SD +/- 3.16). Probands with extreme myopia (-10 DS or worse) showed the highest study participation rate of 56%, when compared to high (-5 DS [ABSTRACT FROM AUTHOR]