A process for manufacturing a film of ultra-high molecular weight polyolefin comprising: (a) subjecting a starting ultra-high molecular weight polyolefin with a weight average molecular weight of at least 500 000 gram/mole in powder form to a compacting step using an isobaric press; and (b) subjecting the compacted polyolefin to a rolling step and at least one stretching step under such conditions that at no point during the processing of the polymer its temperature is raised to a value above its melting point. The process allows for the manufacture of ultra-high molecular weight polyolefin films of high quality.