A 4 year study was conducted to determine the effect of planting date, spacing and potassium on the incidence of hollow heart in Norgold Russet. Hollow heart occurred in 3 of the 4 years; ranging from 5.7 to 45.9% in 1965, 8.2 to 24.1% in 1966 and 0.3 to 3.9% in 1968. depending on treatment. Based on the 4-year averages close spacing, early planting and potassium reduced hollow heart when weather conditions werefavorable for development. Of these treatments close spacing was the most effective control, and planting date was the least consistent in its effect of the factors sudied. In two of the years there was an association between increased numbers of tubers, increased yields and a lower percentage of hollow heart.