A case is reported of successful in-vitro fertilization (IVF) and pregnancy in a natural cycle after four previously failed attempts with stimulated cycles. The patient began treatment at the age of 36 years and underwent four stimulated IVF cycles, each time with three embryos of good quality transferred. In one attempt, three cryopreserved embryos were transferred in a natural cycle. The patient failed to conceive. At the age of 38 years, the patient was entered into a natural cycle IVF programme. The patient conceived twice in each of her first two attempts but unfortunately aborted. In her third natural cycle of IVF, again with one oocyte obtained and one embryo transferred, the patient conceived and had a full term gestation. It is concluded that IVF in a natural cycle is a viable option for infertile women with blocked Fallopian tubes who have normal ovulatory menstrual cycles.