Purpose: This retrospective study was designed to evaluate the appearances of plantar fasciitis by ultrasonography. Materials and Methods: 48 cases of unilateral plantar fasciitis were enrolled in this study. Plain radiograph and realtime sonography of both feet were perfomred and the results were compared between the affected feet and controlateral symptomless feet. Calcaneal spur were observed on plain radiograph and thickness of plantar fascia, hypoechogenecity, blurring of border of plantar fascia, perifascial effusion, wavy plantar fascia were observed on sonography. Results: Women (35 cases) and left feet (30 cases) were more frequent than men and right feet. Thickness of plantar fascia in affected site was thicker than normal site (p<0.01). Hypoechogenecity was observed only in 39 cases (81%) affected site, blurring of border of plantar fascia in affected site was 30 cases (62%) and 7 cases (15%) in normal site, perifascial effusion was observed only in 38 cases (79%) affected site, wavy plantar fascia in affected site was 43 cases (90%) and 2 cases (4%) in normal site. Calcaneal spur in affected site was 36 cases (75%) and 33 cases (69%) in normal site. Conclusion: Sonography is a useful diagnostic procedure for the plantar fasciitis especially in the unilateral plantar fasciitis.