This study investigated the effects of supra-zero storage on ovarian cortex of 12 premenopausal patients before cryopreservation. Fresh ovarian tissue (control) was either vitrified immediately or stored at 4°C for 24 h or 48 h before vitrification. This study assessed malondialdehyde release during storage and the capacity to synthesize oestradiol in culture, follicle morphology and the proportion of apoptotic follicles subsequent to vitrification-warming. The malondialdehyde concentration in the storage medium increased significantly in a time-dependent manner (P = 0.029). Oestradiol release during tissue culture decreased statistically significantly in both storage groups compared with the immediate vitrification group (P = 0.043). The proportion of high-quality follicles was significantly different between the fresh group and the two storage groups (24 h, P < 0.01; 48 h, P < 0.001). The proportion of apoptotic follicles was significantly different between the fresh and immediate vitrification groups (P < 0.05). The 24-h and 48-h groups were not different compared with the other groups. This study provides evidence that storage at supra-zero conditions has detrimental effects on the human ovarian cortex. Storage duration should therefore be limited to a minimum to prevent potential damage.