During 774 spontaneous cycles and 87 cycles of assisted reproduction,
the conception rates were evaluated in 48 infertile couples in whom un
ilateral cryptorchidism was the causal factor. In spite of adjuvant th
erapy of the male partner, the spontaneous conception rate was very lo
w (1% per cycle). Intra-uterine insemination (IUI) and conventional in
vitro fertilization (IVF) resulted in similar success rates of 6.1 an
d 8.7% per cycle/attempt respectively. After intra-cytoplasmic sperm i
njection (ICSI), 46.7% pregnancies were obtained per attempt, and sper
m requirements for the latter treatment to be successful were lower th
an for IUI. It is concluded that subfertility in men with unilateral c
ryptorchidism is severe? conventional IVF has little advantage, but IC
SI is highly successful.