FSHR and Infertility: To overcome the sample-size limitations of previous studies and to reach conclusive evidence, we studied the effect of FSHR Asn680Ser polymorphism (rs6166) on male reproductive parameters in a large study group (n = 1790) involving population-based male cohort from three Baltic countries (n = 1052) and oligo-azoospermic (sperm concentration below 20 × 106/mL) idiopathic infertile patients from Estonia (n = 738).