['To determine if longer storage of embryos in a cryopreserved state negatively affects the chance of successful implantation following thawing and transfer.', 'A retrospective cohort analysis of frozen-thawed embryos that had been donated to recipients. Four time periods were evaluated.', 'No significant decrease in pregnancy or implantation rates was found in the longest freezing group (> or =6 years). In fact, if there was a trend, it was for improved pregnancy rates with longer storage. One of the successes was from embryos stored about 12 years.'] Does length of time of embryo storage negatively influence pregnancy rates after thawing and transfer?