Abstract: Quantum mechanics is, without any doubt, ruling the micro world. In the past century we have become accustomed to the idea that chemistry as we know it is a product of the quantum mechanical properties of electrons. Even the idea that biological phenomena can be traced back to quantum mechanics is not new. About five years ago, spectroscopic experiments on energy transferring pigment-protein complexes active in photosynthetic light-harvesting have demonstrated long lived coherent oscillatory component in the energy transfer dynamics. These oscillations where assigned to a superposition of electronic eigenstates of the photosynthetic machinery, and the debate about the origin of their unexpectedly long life-time has turned into a debate about the importance of quantum effects in photosynthesis and biology at all. In this lecture we will review the status of the research on energy transfer in photosynthesis, and the essence of the controversy about the “quantumness” of photosynthetic systems will be explained. Several theoretical solutions to the problem of the long lived coherence will be provided, both in support of and against the electronic origin of the observed coherence. The question what are the quantum effects required for the function of the photosynthetic apparatus will be addressed based on a simple classical model of photosynthetic antennae.