Seminal vesicle malformations are a rare cause of obstructive azoospermia, often associated with other internal genitalia and upper urinary tract birth defects. We report 5 new cases of seminal vesicle agenesis in men presenting with hypospermia and azoospermia. Imaging showed seminal vesicle unilateral agenesis in all patients. The remaining seminal vesicle was hypoplastic in 3 cases, dilated in 1 case and with abnormally thick content in another case. Vas deferens agenesis was observed unilaterally in 2 patients and bilaterally in 2 other patients. No renal malformations were detected. Genetic study showed in all cases a 46 XY karyotype without any microdeletions. A single heterozygous cystic fibrosis transmembrane regulator gene mutation was diagnosed in 1 man, but not found in his partner. Intracytoplasmic sperm injection using sperm from a testicular biopsy was performed in 3 couples, without success.