Stress has deleterious impact on semen quality and fertility of roosters. This study was investigated to know whether dietary supplementation of organic selenium (oSe) could improve semen quality and fertility of male broiler breeder under dexamethasone (Dexa) induced stress. Forty broiler breeder roosters (64 week of age) were randomly allotted to four groups (10 roosters/group) and fed a standard diet supplemented with different levels of oSe during 10 successive weeks of the experimental period. To induce stress, the birds received injections of 2 mg/kg BW of Dexa during weeks 5 and 6 of the experiment, in one-day-intervals manner. The roosters were not treated with Dexa and oSe (negative control; NC), or treated with Dexa and different levels of oSe including 0 (positive control; PC), 0.30 (Se30+Dexa) or 0.45 (Se45+Dexa) mg/kg diet. Body weight was measured weekly and semen quality parameters and fertility were evaluated every two weeks. Except for seminal volume and total sperm production which was not affected by the treatment, body weight, semen quality parameters, total antioxidant capacity (TAC) and malondialdehyde (MDA) in seminal plasma were influenced by interactive effect of treatment and time (P < 0.05). Dexamethasone injection adversely affected semen quality parameters (semen concentration, motility and plasma membrane integrity) in PC group compared to NC group (P < 0.05); however, dietary supplementation of oSe ameliorated these negative impacts in Dexa-treated roosters (P < 0.05). Fertility was also improved by dietary supplementation of oSe compared to control groups (P < 0.05). These results indicate that although induction of stress have negative effects on rooster semen quality parameters, dietary inclusion of oSe may exert beneficial impact on mitigating the harmful effects of stress on semen quality and fertility rate of broiler breeder roosters.Copyright © 2020 Elsevier Inc. All rights reserved.