To determine the spectrum of CYP1B1 gene mutations in Brazilian patients with primary congenital glaucoma, and to correlate the presence of alterations in the CYP1B1 gene sequence with clinical aspects of the disease.Thirty nonrelated patients with primary congenital glaucoma were studied. Molecular analysis consisted of the codifying region sequencing (exons 2 and 3) and intron/exon boundaries.CYP1B1 gene mutations were present in 9 (30%) of the 30 patients. The structural changes in the CYP1B1 gene previously described in the literature and observed in our study were Q19X, P437L, A443G, g.4340delG, g.7901_79013delGAGTGCAGGCAGA, g.8182delG, and g.8214_8215delG. Three new mutations were observed: 4635delT, 4523delC, and L378Q, in addition to 3793T→C, R48G, A119S, L432V, D449D, and N453S polymorphisms. Patients carrying CYP1B1 gene mutations needed more surgical procedures to control intraocular pressure, either when both eyes were evaluated (P=0.003) or when the worst eye of the patient was analyzed (P=0.011). In relation to the number of affected eyes, all patients with mutations (n=9/9) developed bilateral glaucoma, whereas 11/21 patients without mutations in the CYP1B1 gene had bilateral glaucoma (P=0.013).In this group of primary congenital glaucoma patients, a 30% mutation frequency in the CYP1B1 gene was observed. The presence of mutations was associated with a more severe form of the disease, requiring more surgeries for intraocular pressure control and with a higher rate of bilateral cases.