OBJECTIVE. In patients previously irradiated for head and neck carcinomas, persistent soft-tissue thickening in the larynx and pharynx makes it difficult to distinguish between postirradiation edema and recurrent epidermoid carcinoma. The goal of this work was to characterize the standard double-contrast pharyngographic appearance after irradiation and to differentiate this appearance from that of recurrent or residual neoplasms. MATERIALS AND METHODS. The posttreatment pharyngograms in 43 patients treated with radiotherapy for malignant tumors of the head and neck were retrospectively reviewed. The pharynx had been included in the radiation field in each case. We characterized the posttherapy appearance and identified radiographic signs that could be used to distinguish normal postirradiation edema from recurrent tumor. RESULTS. Soft-tissue thickening of normal laryngeal and pharyngeal structures and laryngotracheal aspiration were common nonspecific findings on posttherapy pharyngograms, each occurring in 39 of 43 patients. Epiglottic enlargement and laryngotracheal aspiration did not correlate with the presence of residual or recurrent neoplasm. Asymmetric swelling was more common ipsilateral to the original neoplasm and did not necessarily indicate a malignant tumor. Mucosal irregularity, ulceration, and a demonstrable focal mass were the only significant predictors of recurrent or residual tumor; at least one of the three findings was present in 17 of 19 patients with neoplasm correctly identified by pharyngography. CONCLUSION. Double-contrast pharyngography is a useful means of diagnosing pharyngeal tumors in patients who have had radiation therapy. Radiographic signs of neoplasm (ulcer, mucosal irregularity, and a focal mass) can be used to distinguish recurrent tumor from nonmalignant changes after irradiation.