New immunofluorescence techniques allow visual identification of human cells in various stages of meiotic prophase. Antibodies to the synaptonemal complex, the centromere and sites of recombination allow these stages of meiotic prophase to be identified. The progress of chromosome synapsis, recombination and associated phenomena such as interference can be studied in normal men, translocation heterozygotes and men with infertility problems. This has greatly stimulated research in human meiosis, leading to many exciting studies on the mechanisms underlying recombination and the generation of chromosome abnormalities.