To establish the profile of patients with acute primary angle-closure glaucoma (APACG) and to assess comparatively clinical and morphometric parameters between eyes with APACG and contralateral eyes (CLEs). Prospective study including patients attended from September 2005 to March 2007. diagnosis of APACG. presence of cataract (except for "glaukomflecken") that may cause low visual acuity or myopization, secondary glaucoma, previous APAGC or surgical procedure in the (CLE), no possibility to control the acute crisis of glaucoma clinically, plateau iris. The following were evaluated: incidence of APACG, age, gender, race, family history of glaucoma, corrected visual acuity (CVA) and uncorrected visual acuity (UVA), spherical equivalent (SE), cup/disc ratio (C/D), gonioscopy, keratometry (K), central corneal thickness (CCT), and echobiometric data [anterior central chamber depth (ACCD), axial length (AL), lens thickness (LT)] and relation between lens thickness and axial length (LT/AL). One thousand and three hundred and forty-three patients were examined from September 2005 to March 2006; 28 (2.1%) had the diagnosis of APACG. The incidence of the APACG was 20.8 cases per 1000 patients. The patients with APACG were manly white women with a negative familial history of glaucoma and with an average age of 59.6 years. When clinical aspects were compared between eyes with APACG and CLEs, statistical significance was observed: UVA (APACG: 0.27 +/- 0.32; CLE: 0.57 +/- 0.33, p=0.000); CVA (APACG: 0.53 +/- 0.44; CLE: 0.88 +/- 0.23, p=0.000); SE (APACG: +0.49 +/- 1.98; CLE: +1.21 +/- 2.03, p=0.007); C/D (APACG: 0.51 +/- 0.28; CLE: 0.42 +/- 0.20; p=0.031). Also, by gonioscopy, eyes with APACG demonstrated more frequently angle closure than CLEs. The eye of the crisis showed the following characteristics: average K of 45.21 +/- 1.96 D, average CCT of 534.46 +/- 34.15 mm, average ACCD of 2.43 +/- 0.28 mm, average AL of 21.68 +/- 0.96 mm, average LT 4.85 +/- 0.32 mm and average LT/AL of 2.24 +/- 0.16. The CLE presented average K of 44.92 +/- 1.86 D, average CCT of 533.18 +/- 31.41 microm, average ACCD of 2.51 +/- 0.29 mm, average AL of 21.82 +/- 0.92 mm, average LT 4.85 +/- 0.36 mm and average LT/AL of 2.23 +/- 0.18. There were statistically significant differences only in two parameters (K and ACCD) when affected and the CLE were compared. The incidence of the APACG was 20.8/1000. It was more frequent in white women, leu kodermics, without family history of glaucoma and with an age average of 59.6 years. The eyes with APACG showed, with statistical significance, worse visual acuity, higher C/D, lower hypermetropic SE, higher average K, and lower ACCD than CLEs.