Under nebular conditions it is expected that the [CaII] lines at 7291.470 and 7323.880 Å should be among the strongest emission lines in the red part of the optical spectrum unless the nebula is matter bounded. The lines are observed in novae, supernovae and some symbiotic systems but the only observation of these lines in planetary nebulae (PN) is for AFGL 618 where the lines are thought to be shock-excited. While higher ionization states of Ca do produce some lines observed in a few high-excitation PN, from which gas-phase Ca abundances averaging to about 5% of solar are found, the CaII lines are not observed even in PN with massive neutral envelopes such as NGC 7027. If the Ca is depleted onto dust grains it would explain the absence of the CaII lines. However it is thought that the dust is destroyed with time in the ionized region. Any observation of the CaII lines would produce better abundance estimates and would test the extent of dust destruction that is taking place in the outer parts of the PN.