Problem　related　to　robust　fault　detection　filter　design　for　a　class　of　networked　systems　with　random　communication　delays　is　discussed　in　this　paper.　The　random　communication　delays　are　modeled　as　a　linear　function　of　the　stochastic　variable　satisfying　Bernoulli　random　binary　distribution　with　an　unknown　conditional　probability　distribution　that　is　assumed　to　be　in　an　interval.　An　observer-based　fault　detection　filter　can　be　designed　to　guarantee　residual　output　sensitive　to　fault　and　robust　to　L2-norm　bounded　unknown　input　and　uncertain　probabilities.　A　sufficient　condition　is　derived　in　terms　of　linear　matrix　inequalities　(LMIs).　A　numerical　example　illustrates　the　effectiveness　of　the　proposed　approach.　©　2008　IEEE.