AIM: To investigate the effects of exogenous testosterone treatment on the choroidal parameters in patients with androgen deficiency. METHODS: Right eyes of 24 patients with androgen deficiency and 31 healthy volunteers were included in the study. The eyes were scanned for subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), choroid-stromal area (C-SA), choroid-luminal area (C-LA), choroid-stromal to luminal area ratio (CSLR), and the choroidal parameters within central 1500 µm of the macula (CVI1500, C-LA1500, C-SA1500, and CSLR1500) by enhanced-depth imaging optical coherence tomography (EDI-OCT) at baseline, 6th and 18th weeks of the exogenous testosterone treatment. RESULTS: The mean SFCT values of the androgen deficient groups and healthy controls were 307.7±27.0 and 303.2±37.2 µm (P=0.8). However, CVI, C-SA, CSLR, CVI1500, C-LA1500, and CSLR1500 were significantly different between the groups (all P<0.01). At the 6th week visit after exogenous testosterone treatment, SFCT, CVI, C-LA, and C-SA were significantly decreased, and these parameters returned to baseline levels at the 18th-week visit (all P>0.05). However, CVI1500 and LA1500 significantly increased at the end of the follow-up period (P<0.001). CONCLUSION: CVI is lower in androgen-deficient patients than in healthy subjects. The alterations in the choroid during the testosterone peak are transient in the treatment of patients with androgen deficiency. However, the increase in CVI within the central 1500 µm of the macula persists even after 4mo.