Nuclear calcium signalling is crucial for important cellular functions including gene expression, protein transport, apoptosis, etc. The Ca²⁺ store in the nuclear envelope has endoplasmic reticulum (ER) characteristics and is connected with the lumen of the ER. Permeability of nuclear pore complexes (NPCs) to Ca²⁺ is still a hot point of many discussions. Our data show that NPCs are open most of the time and even after depletion of the Ca²⁺ store in the nuclear envelope. We also found that all three intracellular messengers NAADP, IP3 and cADPR were equally able to reduce Ca²⁺ concentration inside the nuclear envelope. Reduction of Ca²⁺ in the nuclear envelope was associated with a transient rise in the nucleoplasmic Ca²⁺ concentration in response to all three messengers. Most likely, IP3 and ryanodine receptors located on both inner and outer membrane of the nuclear envelope. We suggest that nuclear envelope contains both ryanodine and IP3 receptors that can be activated separately and independently: the ryanodine receptors by either NAADP or cADPR and the IP3 receptors by IP3.