Seven women with insulin-dependent diabetes (mean age, 26 years; mean duration of diabetes, 15.4 years) had minimal or no retinopathy before becoming pregnant but developed severe macular edema associated with preproliferative or proliferative retinopathy during the course of their pregnancies. The edema was associated with significant macular capillary nonperfusion, and often with significant proteinuria and mild hypertension. Although proliferation was controlled with panretinal photocoagulation, the macular edema continued to worsen until delivery in all cases and was often aggravated by the photocoagulation. Macular edema and retinopathy both regressed after delivery in some patients but persisted in others, causing significant visual loss. Pregnant women with retinopathy, nephropathy, or hypertension should undergo ophthalmoscopy at least once a month. If proliferative retinopathy develops, panretinal photocoagulation should be applied even if the macular edema is aggravated.