Abstract: Spiroplasma citri, the causal organism of citrus stubborn disease is now wide spread in warm regions specially in the Mediterranean area . Spiralin gene is the gene responsible for spiralin which is the major protein of S. citri . IC - PCR method of detection was applied in which the spiroplasma units were captured with the specific polyclonal antibodies on a solid - phase. A specific primers based on the sequence of the Morocco strain of S. citri (R8A2HP) were used. Two primer pairs were used i.e., D, D` which is specific for the whole spiralin gene and SC, SC` which is specific for a fragment of spiralin gene. The two primers amplified 1035 and 330 bp, respectively from infected but not healthy citrus trees. DNA hybridization with DNA probes through Southern blot hybridization technique revealed the sensitivity of this technique for detection of S. citri hi cultures and from infected citrus trees.