The aim of this study was to describe the association between various percentages of macronuclear spermatozoa (MNSs), sperm chromosomal abnormalities, and reproductive failure in 4 patients. One patient had a familial history of perinatal deaths. Patients were selected according to the coexistence of normal-sized spermatozoa and MNSs (19%, 22%, 29.5%, and 49.7%). Fluorescent in situ hybridization (FISH) on spermatozoa and semiautomated analysis of nuclear surface were assessed. All patients were characterized by an oligoasthenozoospermia. Three patients had a prevalence of irregular MNSs and prevalence of nondisjunction at the first meiotic division. One patient had a prevalence of regular MNSs and a prevalence of nondisjunction at the second meiotic division. FISH also showed a high rate of polyploidy and various rates of aneuploid sperm. The percentage of sperm with abnormal chromosome complements (25.6%, 43.6%, 51.4%, 71.7% with 3-color FISH) was higher than the percentage of MNSs. A population of apparently normal-sized spermatozoa that could be used for intracytoplasmic sperm injection (ICSI) was aneuploid. Sperm nuclear surface analysis revealed either a shift toward elevated values or distinguished 2 sperm subpopulations: normal and macronuclear. Patients underwent 7 ICSI cycles. The fertilization rate was low for 3 patients (50%, 40%, 50%) and normal for 1 patient (83.3%). Pregnancy rate per transfer was low (14.3%). The present study shows that the macronuclear phenotype can manifest a variety of clinical aspects. It is also shown that mild rates of MNSs impair fertility and constitute a risk of chromosomal abnormality for the embryos and a risk of perinatal death. We suggest conducting FISH on spermatozoa and genetic counseling for a couple when the percentage of MNSs reaches 20% in at least 1 spermiogram.