To characterize the clinical features associated with XLRS1 gene mutations in Japanese patients with X-linked juvenile retinoschisis (xlRS), we evaluated the following data on 14 Japanese males from 13 unrelated families with XLRS1 mutations: age and symptoms at first visit to an ophthalmologist and ophthalmologic findings including visual acuity, refractive errors, fundoscopic appearance, and results of electroretinography (ERG) and electro-oculography (EOG). Each clinical finding was reviewed when the patients were between six and eight years of age. The best-corrected visual acuity in 12 patients (24 eyes) between the ages 6 and 8 years ranged from 1.0 to no light perception. Macular abnormalities were present in all cases. Peripheral retinoschisis was present in 14 of 26 eyes (53.8%). In the 21 eyes for which a single-flash ERG had been recorded, b-wave amplitude was reduced in 17 eyes. The EOG showed a low Arden ratio in three of the 13 eyes in the seven patients evaluated. No clear relationship was observed between the clinical features and the existing mutations. Three of four patients with a visual acuity less than 0.1 had retinal detachment or severe macular lesion that had occurred before the age of four years. Two patients harbored deletions of exon 1 or of the boundary region between exon 3 and intron 3, and one patient harbored R182C in exon 6. The present study shows a heterogeneity of mutations in the XLRS1 gene and phenotypic variations in 14 Japanese patients with xlRS.