Aims and background: There is considerable evidence from studies on tumor-bearing animals that nutritional support aimed at maintaining a good nutritional status can indeed promote tumor growth. Experience in humans, however, is scanty and controversial, this issue never having been extensively investigated. The purpose of this study was to analyze whether there exists a relationship between nutritional status and tumor growth in patients with non-Hodgkin's lymphoma. The hypothesis behind it was that if it is true than an abundant availability of substrates promotes tumoral growth, then the better the nutritional status the higher the tumor cell proliferation. Methods: Two hundred and forty six adult patients with non-Hodgkin's lymphoma were characterized according to nutritional status (percent of weight loss as compared to usual body weight, serum albumin, serum cholinesterase, number of lymphocytes) and rate of incorporation of H-3 thymidine labelling index in the tumor tissue. The values of serum albumin, serum cholinesterase and lymphocytes were subdivided into three classes adopting as cut-off points the tertile values of their distribution, while weight loss was scored as a ''no'' and a ''yes''. The association between nutritional parameters and labelling index was evaluated by a univariate analysis (X(2) test and Mantel-Haenszel X(2) test and the odds ratio) and by a logistic multiple regression model, Results: Results of the univariate analysis show a statistically significant association between ''poor'' nutritional status (depressed nutritional indexes) and ''high'' labelling index (increased tumoural growth), while the multiple regression analysis found that the only significant association was that between low serum cholinesterase and high labelling index. Conclusions: These data demonstrate for the first time in a large series of patients that maintenance of a good nutritional status does not have any deleterious effect on the tumor growth.