Background: Rapid visual acuity (VA) decline was a common complaint in patients with sellar/suprasellar germinoma. In our hospital, 3.4 Gy/2f of emergency irradiation was applied to save patient VA and enable subsequent chemoradiotherapy. This study aimed to investigate the efficacy of emergency irradiation with 3.4 Gy/2f in patients with sellar/suprasellar germinoma who had rapid VA decline. Methods: From January 2014 to December 2017, 33 patients with sellar/suprasellar germinoma who complained of VA decline within 3 months received 3.4 Gy/2f of emergency irradiation in Beijing Tiantan Hospital. The best-corrected VA (BCVA) and mean deviation (MD) were measured. Correlations between visual function change and clinical factors, including age at diagnosis, duration of VA decline, extent of tumor regression, serum level of tumor markers, were analyzed. Results: Among 33 patients with sellar/suprasellar germinoma, the median diameter and volume of sellar/suprasellar lesions were 32 mm (range: 5-55 mm) and 12.9 cm3 (range 0.6-58.5 cm3), respectively. Data on pre- and post-emergency-irradiation BCVA were obtained in 32 patients. For the right eyes, BCVA was improved in 23 patients (71.9%), unchanged in 7 (21.9%), and worsened in 2 (6.2%); and for the left eyes, these numbers were 27 (84.4%), 4 (12.5%), and 1 (3.1%), respectively. In terms of the logarithm of the minimum angle of resolution (logarithm of the minimum angle of resolution = Log (1/BCVA) score, the improvement was significant in both eyes (P < 0.001). In terms of MD, six patients had paired data and the improvement was marginal in the right eyes (P = 0.068) and significant in the left eyes (P = 0.043). However, no clinical factor was found to have correlation with visual function improvement. Conclusion: In sellar/suprasellar germinoma patients with VA decline, 3.4 Gy/2f of emergency irradiation was effective in improving visual function. Copyright © 2019 The Chinese Medical Association.