Re-offending patterns of a large cohort of offenders released from Florida Department of Corrections custody between 1996 and 2004 were analyzed to quantify the effects of DNA databases on offending patterns. Statistical models constructed to identify the specific deterrent effects of DNA databases distinct from their probative effects yielded mixed results. Small deterrent effects were found and for only some crime types (robbery and burglary). Strong probative effects were found for most crime types. Methods, data, results and implications are discussed in this report.