Global warming, climate change and dwindling fossil carbon resources have lead scientists to look for greener eco friendly alternatives to petroleum derived plastics. This alternative has come in the form of bioplastics and one such prominent family of bioplastics is the polyhydroxyalkanoates (PHAs). PHAs are polyesters of 3, 4, 5 and 6-hydroxyalkanoates produced by many Gram positive and Gram negative bacteria through fermentation of renewable resources. These are accumulated as intracellular inclusions under nutrient limiting conditions. Once extracted, the PHAs exhibit wideranging properties from thermoplastic to flexible elastomeric nature. Biodegradibility and bicompatibility of PHAs are also well established. Owing to these properties PHAs are increasingly attracting interest for commercial exploitation in various agricultural, industrial and medical applications. This chapter discusses how research on PHAs developed and also consolidates curent knowledge on the properties and applications of these PHAs.