Observations in synaptemal complexes in men carrying structural or numerical chromosomal anomalies are reviewed. Chromosome pairing in patients with extra chromosomes, Robertsonian translocations, reciprocal translocations and pericentric inversions is described. Synaptic anomalies in patients with abnormal seminograms, homosynapsis, asynapsis and heterosynapsis and other pairing abnormalities are also discussed.