Results of threshold static perimetry in nine cases of toxic retinopathy produced by chloroquine phosphate and hydroxychloroquine sulfate are reported. Pericentral visual field defects in an advanced case correlated well with ophthalmoscopically visible defects in the pigment epithelium. In a less advanced case, perifoveal defects in the visual field of one eye were found to be demonstrable in the absence of any fundus abnormalities by either ophthalmoscopy or fluorescein angiography. In both cases, visual field defects were deepest on the superior or vertical meridian, just above the point of fixation. Since defects were found to be deepest along the superior vertical meridian, threshold static perimetry that includes this location should be the most sensitive method of detecting the early stages of visual field damage in chloroquine retinopathy.