assuming the death was in Ireland and after the start of civil records in 1864... if you have approx. age, year of death and reasonably detailed location - then you can check the BMD Index on familysearch for possible matches. A research cert from the GRO should help confirm the details - but note that Irish death certs dont show much family information.
BMD Index :
http://goo.gl/VGHDfShane
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