do we need to have a visa to enter Ireland if we have a valid UK student visa?

The provisions of the Common Travel Area only apply to British and Irish citizens. Foreigners must hold a valid passport and (if required) a visa for the Republic or Ireland prior to travel.

http://www.citizensinformation.ie/en/moving_countr... ..

It depends on your (unknown) nationality and on your status in the UK if you need another visa to visit Dublin or other parts of the Republic. Passport holders of Andorra, Antigua & Barbuda, Argentina, Australia, Austria, Bahamas, Barbados, Belgium, Belize, Bolivia, Botswana, Brazil, Brunei, Bulgaria, Canada, Chile, Costa Rica, Croatia, Cyprus, Czech Republic, Denmark, Dominica, El Salvador, Estonia, Fiji, Finland, France, Germany, Greece, Grenada, Guatemala, Guyana, Honduras, Hong Kong (SAR), Hungary, Iceland, Israel, Italy, Japan, Kiribati, Latvia, Lesotho, Liechtenstein, Lithuania, Luxembourg, Macau (SAR), Malawi, Malaysia, Maldives, Malta, Mexico, Monaco, Nauru, Netherlands, New Zealand, Nicaragua, Norway, Panama, Paraguay, Poland, Portugal, Romania, Saint Kitts & Nevis, Saint Lucia, Saint Vincent & the Grenadines, Samoa, San Marino, Seychelles, Singapore, Slovak Republic, Slovenia, Solomon Islands, South Africa, South Korea, Spain, Swaziland, Sweden, Switzerland, Taiwan, Tonga, Trinidad & Tobago, Tuvalu, United Kingdom & Colonies, United States of America, Uruguay, Vanuatu, Vatican City, and Venezuela are generally exempt from the entry visa requirement.

http://www.citizensinformation.ie/en/moving_countr... ..

Passport holder of Bahrain, Belarus, China, India, Kazakhstan, Kuwait, Montenegro, Oman, Qatar, Russia, Saudi Arabia, Serbia, Turkey, Ukraine, United Arab Emirates, or Uzbekistan are exempt from the visa requirement based on the Irish Visa Programme if they hold a short-term type C UK student visitor visa valid for 180 days or less.

http://www.inis.gov.ie/en/INIS/Pages/WP11000005 ..

Those of the above named country who hold a long term type D entry clearance as Tier 4 students must apply for an Irish visa but they are exempt from paying a visa fee.

http://www.inis.gov.ie/en/INIS/VWP%20Info%20NoteRe... ..

All others need to apply for an Irish visa prior to travel. Fee for a single entry: €60 or £53; for multiple entries €100 or £88.

http://www.embassyofireland.co.uk/home/index.aspx?...

If you are from EU you don't need a visa to go to UK (or Ireland). The fact that you have a student visa suggests to me that you are from elsewhere. In that case, yes, you do need a visa to enter Ireland ..... or not, if you are from one of the exempt countries mentioned in GerdP's reply.

Remember that Ireland is a big island. Nothing to stop you entering that island at the bit known as Northern Ireland as that is in the UK.

I think GerdP has given an excellent answer however I am going to reiterate the point that rules of the Common Travel Area do NOT apply to anyone else except British & irish citizens because someone else is bound to leap & say it again as if it's the solution to all travel problems between the islands

http://www.immigrationmatters.co.uk/judge-rules-th...

Probably, as Ireland ISN'T in the United Kingdom.

It is part of the common travel area, no.