user29597: Generally everyone can see all data stored in a blockchain.
Is there any way to handle private personal data like personal medical records which only right person can see?

user5292: I don't see why you would store any data on the block chain instead of just a hash.
The Bitcoin blockchain is not intended (it's actively discouraged) and therefore not suitable for data storage. The distribution system will most likely not suit your needs either. And if you're still not convinced: you're not going to be able to pay for it anyway: Bitcoin transactions cost money per byte, so you want to use as little as possible.
Use some other network/storage system that matches your requirements. Be it a website or bittorrent or a piece of paper.
Whether the actual data there is encrypted or not is your own choice. The blockchain doesn't care.

user12049: You can store data or its hash in the blockchain using OP_RETURN outputs which can store up to 80 bytes http://blog.coinprism.com/2015/02/11/80-bytes-op-return/

29597: <p>Generally everyone can see all data stored in a blockchain.
Is there any way to handle private personal data like personal medical records which only right person can see?</p>
 5292: <p>I don't see why you would store any data on the block chain instead of just a hash.</p>

<p>The Bitcoin blockchain is not intended (it's actively discouraged) and therefore not suitable for data storage. The distribution system will most likely not suit your needs either. And if you're still not convinced: you're not going to be able to pay for it anyway: Bitcoin transactions cost money per byte, so you want to use as little as possible.</p>

<p>Use some other network/storage system that matches your requirements. Be it a website or bittorrent or a piece of paper.</p>

<p>Whether the actual data there is encrypted or not is your own choice. The blockchain doesn't care.</p>
 12049: <p>You can store data or its <strong><em>hash</em></strong> in the blockchain using OP_RETURN outputs which can store up to 80 bytes <a href="http://blog.coinprism.com/2015/02/11/80-bytes-op-return/" rel="nofollow">http://blog.coinprism.com/2015/02/11/80-bytes-op-return/</a></p>
