This paper presents the experimental analysis of porosity in gray iron castings poured with cores prepared with Phenolic urethane no-bake binders. The data for analysis were obtained by altering the casting parameters such as binder ratio, binder level, casting temperature, section size, mixing effect, metal composition, addition of Titanium, Zirconium, Iron oxide, core washes and core post-baking on porosity formation in gray iron castings. Results obtained showed that pouring temperature above 1482 o C, poor binder dispersion and use of binder ratio favouring higher level of polyisocyanate component of the binder promotes porosity. However the additions of 0.25% red iron oxide (Fe 2 O 3 ), 0.025% Titanium and 0.05% Zirconium were also effective in eliminating porosity just as core post-baking and the use of core coating modified with red iron oxide. This result will help metal casters to reduce porosity defects in gray iron castings when they are poured with cores prepared with Phenolic urethane no-bake binders.