Madagascar periwinkle (Catharanthus roseus [L.] G. Don), a perennial and evergreen herb in the family Apocynaceae, is an ornamental and medicinal plant in subtropical and tropical regions of the world. Madagascar periwinkle is also a useful model plant for studying phytoplasma–host interactions. These phytopathogenic mollicutes are transmitted by homopteran insects, mainly leafhoppers and less frequently psyllids, and can cause serious diseases in crops and ornamentals plants worldwide. In late February 2018, phytoplasma-like symptoms such as yellows, stunted growth and phyllody were observed on periwinkle plants grown in the urban green space of the Jiroft city, southern Kerman province. Leaf samples were collected from the symptomatic and asymptomatic periwinkle plants. Leaf midribs of the samples were cut with sterile razor blades and the total nucleic acid was extracted using the CTAB buffer method. Phytoplasma infection was checked using nested polymerase chain reaction assays with specific primer pairs P1/P7 followed by R16F2n/R2 for the amplification of phytoplasma 16S rRNA gene. The DNA sample of witches’-broom phytoplasma was also used as a positive control. DNA amplification with the primer pairs P1/P7 and R16 F2n/R2 gave the expected amplified products of 1.8 and 1.2 kb, respectively. Identical fragments were also amplified from the positive control. No amplification products were obtained from asymptomatic periwinkle plants. The results indicated a direct association between phytoplasma infection and the periwinkle phyllody disease. Meanwhile, the taxonomic status and group classification of the causal agent of the disease is under study. This is the first report of the natural infection of periwinkle plants by phytoplasmas in Kerman province.