This　paper　reports　an　experimental　investigation　on　flow　resistance　characteristics　associated　with　the　forced　flow　of　de-ionized　water　through　circular　and　diamond　shaped　micro　pin　fin　arrays.　Comparing　with　circular　pin　fin　arrays,　diamond　shaped　pins　produce　higher　friction　factors.　By　comparing　the　current　data　with　results　available　in　the　literature,　it　can　be　concluded　that　the　conventional　long　tube　correlations　are　unable　to　predict　the　friction　factor　for　micro　pin　fin　arrays.　According　to　the　experimental　data,　several　new　correlations　for　friction　factor　and　Reynolds　number　of　staggered　pin　fin　arrays　were　developed.　©　2010　American　Institute　of　Physics.