Objective To investigate the risk of storage lesion of suspended erythrocyte membrane without leukocyte with prolonged storage time. Methods From May to June 2013, 6 bags of suspended erythrocyte without leukocyte which were prepared at Hebei Blood Center were collected as research objects in this study by random sampling method. On day 7, 14, 28 and 42 of storage, the ultrastructure changes of suspended erythrocyte without leukocyte were observed by scanning electron microscopy. Four views were selected randomly to count double concave disc suspended erythrocyte and suspended erythrocyte with spines. The mean corpuscular volume (MCV) of suspended erythrocyte without leukocyte was detected with blood cell analyzer, and the content of free hemoglobin (FHb) outside suspended erythrocyte without leukocyte was detected with chemical colorimetry. Correlation analysis between MCV, FHb concentration outside of suspended erythrocyte without leukocyte and storage time was carried out by statistical methods. Results The changes of suspended erythrocyte without leukocyte were as followed. ①With the extension of storage time, the number of double concave disc suspended erythrocyte without leukocyte reduced gradually, but the number of suspended erythrocyte with spines increased gradually. ②On day 7, 14, 28 and 42 of storage, MCV of suspended erythrocyte without leukocyte showed a significant increasing trend. And the MCV of suspended erythrocyte without leukocyte on day 42 was significantly higher than that on day 7, 14 and 28 (P<0.01, 0.01, 0.05). There was a positive correlation between the MCV of suspended erythrocyte without leukocyte and its storage time (r=0.899, P<0.01). ③On day 7, 14, 28 and 42 of storage, FHb concentration outside suspended erythrocyte without leukocyte showed a significant increasing trend, FHb concentration outside suspended erythrocyte without leukocyte on day 42 was significantly higher than that on day 7, 14 and 28 (P<0.01). There was a positive correlation between the FHb concentration outside suspended erythrocyte without leukocyte and storage time (r=0.969, P<0.01). Conclusions With the extension of storage time, the normal morphology of most of the suspended erythrocyte without leukocyte disappear gradually, the MCV and extracellular FHb concentration increase significantly. This shows that the damage degree of suspended erythrocyte membrane without leukocyte increase gradually with the extension of storage time. Key words: Erythrocytes; Cell membrane; Mean corpuscular volume; Hemoglobin, free; Ultrastructure