Basic calcium phosphate (BCP) crystals, including octacalcium phosphate (OCP), carbonated-apatite (CA) and hydroxyapatite (HA) crystals are associated with destructive forms of osteoarthritis. Mechanisms of BCP-induced cartilage breakdown remain incompletely understood. We assessed the ability of BCP to induce changes in intracellular calcium (iCa 2+ ) content and oscillations and the role of iCa 2+ in BCP-induced cartilage degradation.Bovine articular chondrocytes (BACs) and bovine cartilage explants (BCEs) were stimulated with BCP or monosodium urate (MSU) crystals. iCa 2+ levels were determined by spectrofluorimetry and oscillations by confocal microscopy. mRNA expression of matrix metalloproteinase 3 (MMP-3), a disintegrin and metalloprotease with thrombospondin-like motifs 4 (ADAMTS-4) and ADAMTS-5 was assessed by quantitative real-time PCR. Glycosaminoglycan (GAG) release was measured in the supernatants of BCE cultures.All three BCP crystals significantly increased iCa 2+ content. OCP also induced iCa 2+ oscillations. Rate of BACs displaying iCa 2+ oscillations increased over time, with a peak after 20 min of stimulation. OCP-induced iCa 2+ oscillations involved both extracellular Ca 2+ (eCa 2+ ) influx and iCa 2+ stores. Indeed, OCP-induced iCa 2+ oscillations decreased rapidly in Ca 2+ -free medium. Both voltage- and non-voltage-dependent Ca 2+ channels were involved in eCa 2+ influx. BCP crystal-induced variation in iCa 2+ content was associated with BCP crystal-induced cartilage matrix degradation. However, iCa² + was not associated with OCP crystal-induced mRNA expression of MMP-3, ADAMTS-4 or ADAMTS-5.BCP crystals can induce variation in iCa 2+ content and oscillations in articular chondrocytes. Furthermore, BCP crystal-induced changes in iCa 2+ content play a pivotal role in BCP catabolic effects on articular cartilage.