PURPOSE: To assess the astigmatic effect of biaxial microincision cataract surgery (MICS) with insertion of an UltraChoice 1.0 Rollable Thinlens intraocular lens (IOL) in a sufficiently powered controlled study. SETTING: Queen Elizabeth Hospital, South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, Australia. METHODS: Consecutive patients having biaxial MICS were evaluated prospectively. Keratometry was performed preoperatively and postoperatively. Vector analysis of the alteration in the keratometric cylinder was compared with that in control eyes not having surgery but having keratometry over a similar time frame. RESULTS: There were 76 eyes in the surgical group and 74 in the control group. The right-hand incision used for IOL insertion had a mean external opening width of 2.00 mm and a mean internal width of 1.89 mm. The left-hand incision measured a mean of 1.49 mm and 1.46 mm, respectively. There was no statistically significant difference between the surgical group and the routine variability in keratometry in the untreated control group in surgically induced astigmatism (surgical group, 0.57 diopter [D] +/- 0.05 [SEM]; control group, 0.54 +/- 0.06 D; P =.660) or the degree of mean calculated flattening effect at the right-hand incision (0.01 +/- 0.06 D and -0.05 +/- 0.05 D, respectively; P = .405) or at the left-hand incision (-0.06 +/- 0.05 D and 0.03 +/- 0.06 D, respectively; P = .283). CONCLUSION: Biaxial MICS with insertion of IOL through a temporal incision of 2.0 mm offers prospects of astigmatic neutrality in cataract surgery.