Purpose: To compare outcomes of microincision cataract surgery (MICS) with coaxial phacoemulsification. Design: Prospective randomized consecutive case series. Participants: One hundred eyes of 50 patients with nuclear or corticonuclear cataract (grades 2+to 4) with Lens Opacities Classification System III. Methods: One hundred eyes (50 patients) were randomly operated through clear corneal incisions using 2 techniques: coaxial phacoemulsification (50 eyes) and microincision cataract surgery (50 eyes). Main Outcome Measures: Mean phacoemulsification time, total phacoemulsification percent, effective phacoemulsification time (EPT) (calculated by multiplying total phacoemulsification time in seconds by the average power percent used), intraoperative total balanced salt solution (BSS) volume, visual outcome, vectorial astigmatic changes, corneal thickness, endothelial cell count, and anterior chamber flare and cells preoperatively and at 1 day, 1 month, and 3months. Results: Statistically significant differences were found between MICS and coaxial phacoemulsification regarding mean incision size, mean total phacoemulsification percent, and EPT. There were no significant differences between the techniques regarding the mean percent of endothelial cell loss, anterior chamber cell count and flare, mean phacoemulsification time, pachymetric measures or total BSS volume utilized, or visual outcome. The vectorial astigmatic changes in the MICS group showed a change of ≤0.25 diopters (D) in 35%of the eyes, 0.25 to 0.5 D in 50%of the eyes, and 0.5 to 1.0 D in 15%of the eyes. These changes were induced by the surgery. Vectorial astigmatic changes of >1 D were not observed. In the coaxial phacoemulsification group, vectorial astigmatic changes of < 0.25 D were not observed either. Changes of 0.25 to 0.5 D were seen in 20%of the eyes, and changes of 0.5 to 1.0 D were seen in 30%. Fifty percent of the eyes showed changes of >1.0 D. Mean vectorial astigmatic changes were 0.36±0.23 D in the MICS group and 1.2±0.74 D in the coaxial phacoemulsification group (P< 0.001). Conclusions: Microincision cataract surgery significantly lowered mean phacoemulsification time,mean total phacoemulsification percent, mean EPT, and surgically induced astigmatism when compared with coaxial phacoemulsification. Purpose: To compare outcomes of microincision cataract surgery (MICS) with coaxial phacoemulsification. Design: Prospective randomized consecutive case series. Participants: One hundred eyes of 50 patients with nuclear or corticonuclear cataract (grades 2 + to 4) with Lens Opacities Classification System III . Methods: One hundred eyes (50 patients) were randomly operated through clear corneal incisions using 2 techniques: coaxial phacoemulsification (50 eyes) and microincision cataract surgery (50 eyes). Main Outcome Measures: Mean phacoemulsification time, total phacoemulsification percent, effective phacoemulsification time (EPT) (calculated by multiplying total phacoemulsification time in seconds by the average power percent used), intraoperative total balanced salt solution (BSS) volume, visual outcome, vectorial astigmatic changes, corneal thickness, endothelial cell count, and anterior chamber flare and cells preoperatively and at 1 day, 1 month, and 3months. Results: Statistically significant differences were found between MICS and coaxial phacoemulsification regarding mean incision size, mean total phacoemulsification percent, and EPT. There were no significant differences between the techniques regarding the mean percent of endothelial cell loss, anterior chamber cell count and flare, mean phacoemulsification time, pachymetric measures or total BSS volume utilized, or visual outcome. The vectorial astigmatic changes in the MICS group showed a change of ≤ 0.25 diopters (D) in 35% of the eyes, 0.25 to 0.5 D in 50% of the eyes, and 0.5 to 1.0 D in 15% of the eyes. These changes were induced by the surgery. Vectorial astigmatic changes of> 1 D were not observed. In the coaxial phacoemulsification group, vectorial astigmatic changes of <0.25 D were not observed either. to 0.5 D were seen in 20% of the eyes, and changes of 0.5 to 1.0 D were seen in 30%. Fifty percent of the eyes showed changes of> 1.0 D. Mean vectorial astigmatic changes were 0.36 ± 0. twenty threeD in the MICS group and 1.2 ± 0.74 D in the coaxial phacoemulsification group (P <0.001). Conclusions: Microincision cataract surgery Polarization mean phacoemulsification time, mean total phacoemulsification percent, mean EPT, and surgically induced astigmatism when compared with coaxial phacoemulsification.