Abstract: Example data leakage detection apparatus disclosed herein include a fingerprinter to generate a first data fingerprint of a first data item accessed from a data source. Disclosed example data leakage detection apparatus also include a blockchain scanner to scan a blockchain to detect whether a first blockchain record includes a second data fingerprint that matches the first data fingerprint of the first data item. Disclosed example data leakage detection apparatus further include a blockchain writer to write a second blockchain record to the blockchain when the second data fingerprint matches the first data fingerprint, the second blockchain record to indicate the first data item is associated with a data leak of a protected data item represented by the second data fingerprint. In some examples, the second blockchain record is to include the first data fingerprint and a first timestamp.