International preliminary examination is an optional part of the processing of an international application, performed if the applicant files a "demand". The aim of the international preliminary examination under Chapter II of the PCT is not to be granted or refused a patent, but to obtain a preliminary and non-binding opinion on whether the claimed invention appears to be novel, to involve an inventive step and to be industrially applicable.

A secondary objective is to identify whether there appear to be any defects in the form or contents of the international application, for example with regard to the clarity of the claims, the description, and the drawings, or whether the claims are fully supported by the description. The results of the international preliminary examination are recorded in the International Preliminary Report on Patentability (IPRP Chapter II). 

The International Preliminary Report on Patentability established by the International Preliminary Examination Authority (IPEA) provides the applicant with a good basis on which to evaluate the chances of obtaining patents in the various Offices in the national phase.