Many trials are being made for oestrus detection and reducing the lime (or this. In recent years, oestrus synchronisation programs were developed which different hormones are used alone or together Because o I application easiness, providing the artificial insemination of cow with suboestrus and preventing the time and effort waste tor oestrus detection, oestrus synchronisation programs which used with fixed-time artificial insemination are prefered in field conditions. Explaining advantages and disadvantages and choosing the most suitable method of synchronisation programs which used with fixed-time artificial insemination is very important to benefit from cattle population