The increasing implementation of multicentre studies has led to a need for the optimization of a method that allows for accurate post-hoc analysis of patient biological samples. Assessment of total cell number, viability and immunophenotype can present logistical challenges which can be aided by batch processing. The increased sample storage time that this requires necessitates the use of reagents to preserve cellular integrity, viability and immunophenotype. TransFix is a stabilising reagent that has been developed for the preservation of cell numbers and cell marker expression in peripheral whole blood for up to ten days. This study investigated the use of TransFix reagent for the preservation of the stromal vascular fraction (SVF) of collagenase digested adipose tissue. It was demonstrated that TransFix was suitable for accurately measuring nucleated SVF cell numbers for up to seven days as well as back calculating original cell viability. It also stabilised three CD markers commonly used to identify populations within SVF (CD90, CD31 and CD45) for up to seven days. There was no significant difference between the number of CD90, CD31 and CD45 positive cells after stabilisation at Day 7 compared to Day 0 unstabilised samples. The results suggest that TransFix can be used to preserve a biological mixed cell population from human adipose-derived SVF for up to seven days for accurate post-hoc analysis.