Introduction: Sputum cytology is a well-established technique for the detection of lung malignancies. Generally, random or morning samples are used. Objectives: To evaluate the diagnostic yield of morning sputum and compare it with that of fresh samples. Materials and Methods: Patients were instructed to bring a morning sputum sample to the laboratory in a clean plastic container, without any fixative and within 2-3 h of collection. Fresh sputum was then collected in the laboratory from these same patients. Two smears were prepared from each sample by the “pick and smear” technique and then stained by the Papanicolaou method. One hundred samples from each method (total 200 samples; 400 slides) were evaluated by 3 investigators for their adequacy, preservation, and yield of diagnostic cells. The results were analyzed by using the Pearson χ2 test. Results: Cytomorphological details were preserved in 82/84 satisfactory morning samples and in 80/81 satisfactory fresh samples, respectively. Malignancy was detected in 37 morning samples (44%) and 25 fresh samples (30.8%). In the malignant samples, there were more abundant tumor cells in the morning samples than in the fresh samples (65 and 40%, respectively) with a 2+ cellularity in the morning samples. The morning samples showed a better cell yield (25% more), with a 13% increase in the rate of detection of malignancy and an increased sensitivity of 19.68% compared to the fresh samples. Conclusions: Adequacy and preservation was similar in both sample types. While the morning samples showed a higher sensitivity and a larger number of tumor cells than the fresh samples, the difference was not statistically significant (p < 0.054).