In a 3-year field study on a commercial lettuce farm in the Palatinate, Germany, a total of 125 harvests of butterhead lettuce was assessed for tipburn. The tipburn assessments were related to growth data and climatic variables that were collected from a weather station in the vicinity of the fields. Highly significant positive linear regression coefficients between tipburn severity and the sum of irradiation, the head fresh weight, the sum of temperature, the sum of maximum daily irradiation, and the day-light length 23 days prior to harvest were obtained. Of these variables the sum of irradiation from planting to harvest not only had the highest correlation coefficient (r=0.484, n=125) but was also the only variable which was significantly correlated with tipburn in every single year. Moreover, the sum of irradiation remained a highly significant predictor for tipburn if other variables were statistically eliminated by partial regression analysis. In reverse, the significance of the other variables, e.g. head fresh weight at harvest, was lost if the sum of irradiation was eliminated statistically by means of partial regression analysis. Further analysis of the light effect in a timely resolution indicated, that high irradiation particularly 3–4 weeks prior to harvest seems to cause tipburn. Multiple regression analysis lead to no satisfactory prediction of tipburn for practical usage. For example, as many as 11 variables were necessary to yield a coefficient of determination of only 0.57. By statistical means this study for field grown lettuce suggests a light effect on tipburn beyond that of growth. Additionally, certain threshold values for other variables could be established above which the likelihood of tipburn may be increased. In this study, neither the NO 3 content of heads, nor the residual inorganic nitrogen in the soil at harvest was related with tipburn.