To study morphologic changes of serous retinal detachment (SRD) and hyperreflective dots, which have been reported to be precursors of hard exudates, detectable in SRD using optical coherence tomography (OCT) to assess whether or not the OCT findings are correlated with the subfoveal deposition of hard exudates in patients with diabetic macular edema (DME) accompanied by SRD. Retrospective chart review. Twenty-eight eyes of 19 patients with DME accompanied by SRD. We imaged SRD and the hyperreflective dots in SRD using spectral domain OCT (SD-OCT). The number and distribution of the hyperreflective dots in SRD were evaluated before the initial treatment at our hospital for DME accompanied by SRD. Based on a difference in the SD-OCT findings, the study eyes were divided into 2 groups: eyes with a few dots and those with many dots. We studied the clinical course of these 2 groups to assess whether or not the findings of SRD and hyperreflective dots on the SD-OCT images were correlated with deposition of hard exudates in the subfoveal space during follow-up. Correlation of the SD-OCT findings of SRD and hyperreflective dots with deposition of hard exudates in the subfovea of patients with DME accompanied by SRD. Subfoveal deposition of hard exudates was seen in 11 of the 28 eyes at the final examination. Before initial treatment at our hospital, 14 eyes had a few hyperreflective dots SRD and 14 eyes had many hyperreflective dots. Whereas no deposition of hard exudates in the subfoveal space was seen in the former eyes, it was seen in 11 of the latter 14 eyes (P < 0.0001). In addition, using SD-OCT, we found discontinuity of the outer border of detached neurosensory retina in 9 of the 28 eyes. Of these 9 eyes, 1 was in the group with few hyperreflective dots and eight were in the group with many hyperreflective dots (P = .0046). In patients with DME accompanied by SRD, SD-OCT revealed that hyperreflective dots may be associated with the subfoveal deposition of hard exudates during follow-up.