A soft tissue filler composition comprising: a crosslinked hyaluronic acid component comprising a crosslinked mixture of (i) a first, low molecular weight HA material having an average molecular weight of between 0.20 MDa and 0.99 MDa, and (ii) a second, high molecular weight HA material having an average molecular weight of between 1.0 MDa and 4.0 MDa; wherein: the average molecular weight of the second, high molecular weight HA material is at least twice that of the first, low molecular weight HA material; the HA materials are hyaluronic acid or one or more salts thereof; the crosslinked HA component has a HA material concentration of between 15.0 mg/g and 20.0 mg/g; the crosslinked mixture contains more than 50% w/w of the first, low molecular weight HA material; and the crosslinking is achieved by the use of a crosslinking agent; and an uncrosslinked HA solution which comprises between 27 mg/g and 33 mg/g of uncrosslinked HA or a salt thereof having an average molecular weight of between 1.0 MDa and 4.0 MDa, and which is present in the composition in an amount of at least 0.5% w/w and less than 5.0% w/w; wherein each average molecular weight is calculated using the following equation: MW = η / 9.78 × 10 − 5 1.45 wherein n is the intrinsic viscosity in m 3 /kg of the HA material, as measured using the method defined in the European Pharmacopoeia (Ph.Eur.), monograph no. 1472, 01/2009. a crosslinked hyaluronic acid component comprising a crosslinked mixture of (i) a first, low molecular weight HA material having an average molecular weight of between 0.20 MDa and 0.99 MDa, and (ii) a second, high molecular weight HA material having an average molecular weight of between 1.0 MDa and 4.0 MDa; wherein: the average molecular weight of the second, high molecular weight HA material is at least twice that of the first, low molecular weight HA material; the HA materials are hyaluronic acid or one or more salts thereof; the crosslinked HA component has a HA material concentration of between 15.0 mg/g and 20.0 mg/g; the crosslinked mixture contains more than 50% w/w of the first, low molecular weight HA material; and the crosslinking is achieved by the use of a crosslinking agent; and the average molecular weight of the second, high molecular weight HA material is at least twice that of the first, low molecular weight HA material; the HA materials are hyaluronic acid or one or more salts thereof; the crosslinked HA component has a HA material concentration of between 15.0 mg/g and 20.0 mg/g; the crosslinked mixture contains more than 50% w/w of the first, low molecular weight HA material; and the crosslinking is achieved by the use of a crosslinking agent; and an uncrosslinked HA solution which comprises between 27 mg/g and 33 mg/g of uncrosslinked HA or a salt thereof having an average molecular weight of between 1.0 MDa and 4.0 MDa, and which is present in the composition in an amount of at least 0.5% w/w and less than 5.0% w/w; wherein each average molecular weight is calculated using the following equation: MW = η / 9.78 × 10 − 5 1.45 wherein n is the intrinsic viscosity in m 3 /kg of the HA material, as measured using the method defined in the European Pharmacopoeia (Ph.Eur.), monograph no. 1472, 01/2009.