Periwinkle (Catharanthus roseus L.) is an ornamental and therapeutic herbaceous subshrub. The available literature on inheritance of flower colour in periwinkle is meager. The present investigation was conducted at the Punjab Agricultural University, Ludhiana to exploit the genetic inheritance of flower colour and to determine the number of genes involved in the inbred lines of periwinkle by crossing of an accession Vi-15-1 possessing magenta with white centre corolla and another accession Vi-29 possessing white corolla. The all F₁ plants developed from crossing, including reciprocal were shown pale purple coloured flowers. In the F₂ generation, three types of plants were generated such as magenta with white centre corolla (O^mO^m), pale purple corolla (O^mW) and white (WW) corolla in the ratio of 1:2:1. The results indicate that magenta corolla shows incomplete dominance over white corolla which is possibly governed by a single pair of gene. The reciprocal cross reported the same results indicating no involvement of the cytoplasmic genes in this process. Since it is crucial to improve the landscaping traits genetically in periwinkle hence, in light of this; the present study on inheritance of corolla colour may be able to serve as future reference for the valuable genetic research.