The aim of this study was to investigate how much the advice and communication related to food intake in lung cancer patients helped in the improvement of the nourishment. Thirty (30) patients from the oncological hospital “Agioi Anargyroi” were participate in our study. These patients were selected according to defined criteria, 15 from them received advice about their diet (intervention group), while 15 did not (control group). All the patients were without metastasis and generally in good condition. The general conditions of the patients were evaluated according to the ECOG scale. Blood samples were used as nutritional markers, such as: hemoglobin, hematocrit, total proteins, serum albumin and serum globulin. The interventions were a type of nutritional instructions which were recommended to patients given to them and to their families through personal contacts. The majority of patients comprehended and applied the directions. The dietary interventions/instructions and the evaluation of the patients’ condition as well as the blood tests took place when chemotherapy had been scheduled, six times for each patient, every 21 days. The results showed that the general condition of the patients in the intervention group appears better during the duration of chemotherapy and particularly at the 3rd cycle. The values of the nutritional markers tested presented a gradually decrease in both groups. Comparing the two groups, changes from the 1st to the 6th cycle were observed, favorable to the intervention group, but without finding statistical difference. The change in total proteins from the 1st to the 6th cycle presented a smaller decrease in the intervention group by 26.49%. Concluding, it was shown that the instructions for nutritional intervention had a favorable effect on the nourishment of the patients with lung cancer who were administered chemotherapy, although there were not significant differences between intervention and control group. The intervention provided a temporary maintenance of nourishment and a form of psychological support. So that, it seems that it would be beneficial for patients with malignancies if it would be applied in clinical practice.