The present invention relates to a method for processing microbiologically produced, non-polar, cyclic oligopeptides comprising the step of a) extracting the entire fermentation broth incident to the microbiological production process using a liquid extractant that contains ether and is immiscible with water, wherein the amount of extractant is sufficient to form a two-phase system together with the total fermentation broth, and novel solvates of cyclosporin A and methyl-t-butyl ether.