We present a theory of magnetotransport phenomena related to the chiral anomaly in Weyl and Dirac semimetals. We show that conductivity, thermal conductivity, thermoelectric and the sound absorption coefficients exhibit strong and anisotropic magnetic field dependences. In the presence of a magnetic field the Wiedeman-Franz law in these materials can be violated. We also discuss properties of magneto-plasmons and magneto-polaritons, whose existence is entirely determined by the chiral anomaly. Finally, we discuss the conditions of applicability of the quasi-classical description of electron transport phenomena related to the chiral anomaly.