To provide evidence for diagnosing malignant glaucoma, as well as to elucidate the pathogenetic mechanism of the disease, ultrasound biomicroscopy (UBM) is a useful tool. We examined the anterior segments of three patients with post-operative malignant glaucoma with UBM regarding the state before operation, the state of the opposite eye, and the state after the release of the cilio-lenticular block. Case 1 was a 76-year-old female who was diagnosed as having chronic angle-closure glaucoma (CACG) and was treated by trabeculectomy, phacoemulsification, aspiration (PEA), and simultaneous intraocular lens (IOL) implantation. Case 2 was a 22-year-old male diagnosed as having CACG secondary to plateau iris syndrome and was treated by trabeculectomy. Case 3 was a 73-year-old female diagnosed as having normal-tension glaucoma with narrow angle and was treated by PEA and IOL implantation. Slit-like anterior chamber angle and anteriorly positioned ciliary body were observed in all 3 cases, which were identical to those Pavlin reported in 8 cases with plateau iris syndrome. UBM seems to be an important pre-operative examination to evaluate the risk of malignant glaucoma and to consider which surgical procedure and post-operative management is proper. The pre-operative configuration of the ciliary body may be associated with the onset of malignant glaucoma in some patients with CACG or narrow angle.