Malignant ovarian germ cell tumours (MOGCT) principally occur in girls and young women and are generally unilateral. Effective combination chemotherapy with conservative surgery has seen a dramatic improvement in survival rates. This increase has shifted the focus to long-term fertility and reproductive outcome. The present study describes 45 patients with MOGCT treated with conservative surgery to preserve fertility, with or without the addition of chemotherapy. The age range was 10 to 32 years with a mean of 20 years. The majority of the subjects had Stage 1 tumours; 44 underwent unilateral salpingo-oophorectomy and 1 patient ovarian cystectomy. Adjuvant chemotherapy was administered in 29 patients. Overall mean follow-up was 58.7 months. There were 4 recurrences and 2 deaths. Survival of those with Stage 1 disease was 97% and for advanced stages 87%. During chemotherapy 50% became amenorrhoeic but 96% resumed normal menstrual function on completion. Seven healthy babies were recorded in the chemotherapy group and no documented birth defects occurred in any of these. There was no case of persistent infertility; 3 patients experienced temporary problems. It is concluded that conservative fertility-sparing surgery is the treatment of choice in these young women and advanced disease is not necessarily a contraindication. The majority can anticipate normal menstrual function and fertility.