A Romaine lettuce variety with improved resistance to corky root disease and lettuce dieback disease is presented. The seed of the lettuce is designated as PYB 1595, a representative sample of which has been deposited under ATCC Accession Number PTA-9179. PYB 1595 is a medium-dark green Romaine lettuce that combines the above disease resistance with Parris Island Cos (PIC) plant type. The invention is also directed to a method of making an F1 hybrid lettuce variety by crossing a plant grown from the seed of PYB 1595 with another plant and selecting a seed from said crossing.