Subfertility is a statistical concept. When a pregnancy has not been achieved within a year of unprotected intercourse, the odds are that an underlying pathological mechanism is at play. Advanced female age, longer duration and primary infertility, are important prognostic factors, suggestive of low fecundity and indicating a need for further diagnosis and treatment. Many diagnostic tests only have screening value and the only gold standards are hysteroscopy and laparoscopy. Severely impaired semen quality should lead to andrological work-up. Postcoital test and endometrial biopsy are obsolete. Treatment should preferably be aetiological, such as in anovulation, and sometimes also in endometriosis and tubal infertility. Primary treatment of male infertility is not proven to be advantageous. Conception-enhancing techniques such as intrauterine insemination (IUI), in vitro fertilisation (IVF) with or without intracytoplasmic sperm injection (ICSI), have shown to be effective. As a rule, and where possible, IUI is preferred and only if four to six cycles have failed should IVF be offered.