The invention provides seeds and plants of cucumber inbred line API-M318-0803GY. The invention thus relates to the plants, seeds, plant parts, and tissue cultures of cucumber inbred line API-M318-0803GY and to methods for producing a cucumber plant produced by crossing such plants with themselves or with another plant, such as a cucumber plant of another genotype. The invention further relates to seeds and plants produced by such crossing. The invention further relates to plants, seeds, plant parts, and tissue cultures of cucumber inbred line API-M318-0803GY comprising introduced beneficial or desirable traits.