Use of alginates for preparing a non-crosslinked, highly pure and high molecular alginate solution (sol) (I) as filler material in medicine or cosmetic for increasing volume, is claimed, where 0.5-2.5 vol.% of alginate is present in (I) and when (I) is injected in vivo, (I) spontaneously results in in-situ calcium (Ca 2>;+>;) crosslinking without exogenous addition of crosslinkers. ACTIVITY : Dermatological; Antiinflammatory; Uropathic; Cytostatic. MECHANISM OF ACTION : None given.