Comets may have played an important role in depositing the organic matter that, between 4,6 and 3,6 billion of years ago, allowed the formation of life on the primordial Earth. Nowadays, many complex organic molecules are routinely observed in the gaseous component of the comae by radio and near-IR observations. However a large quantity of organic matter may be under the form of solid, either as organic grains or organics embedded in silicate grains. The Giotto mission to the 1P/Halley comet revealed for the first time the in-situ presence of organic grains, that accounted for almost 50% of the mass of organic matter in its coma. Remote detection of these organic grains in other comets is very difficult because they rapidly sublimate under the solar radiation and their spectroscopic signatures are hidden within those of the refractory cometary dust. In this talk I will give a short review on the organic matter in comets, I will describe a method for detecting organic grains in comets and I will present recent results.