Propylene glycol (PG) is a common humectant added to the tobacco used in cigarettes, and part of this compound is transferred to smoke. The influence of this additive on the retention of solanesol by smokers has been evaluated in the present study for two cigarettes having the same tobacco blend except for the 3% addition of PG on one of them. The cigarette with no PG was a commercial brand, and the experimental one was made using the same tobacco blend as the commercial cigarette, but adding 3% of PG. The construction of the cigarette with 3% PG allowed to match as close as possible the 'tar' [as measured by Federal Trade Commission (FTC) regimen], pressure drop (open and closed), and nicotine level of the commercial cigarette. The number of human subjects taking the test was ten smokers for each of the two evaluated products. The sample collection was performed from three cigarettes smoked within one hour. The same human subject smoked the regular cigarette and then the one with added PG. The exhaled smoke was collected using a vacuum assisted procedure that avoids strain in exhaling, and the solanesol was analyzed using an high performance liquid chromatography (HPLC) technique. The cigarette butts from the smokers were collected and also analyzed for solanesol. The results obtained for the cigarette butts from the smokers were used to calculate the level of solanesol in the smoke delivered to the human subject, based on calibration curves. These curves were generated separately by analyzing the solanesol in smoke and in the cigarette butts obtained by machine smoking under different puffing regimes. Knowing the delivered amount of solanesol and that in the exhaled smoke it was possible to calculate the retention of this compound from mainstream smoke for the two cigarette types. The levels of solanesol delivered to the smoker from Cigarette A was in the range between 350.4 µg/cig and 504.8 µg/cig for the cigarette with no PG, and between 401.5 µg/cig and 614.1 µg/cig for the cigarette with 3% PG added. The amount of solanesol retained by the smoker (per cigarette) was on an average 309 µg/cig with 15.8% relative standard deviation for the cigarette with no PG, and an average of 348 µg/cig with 20.4% relative standard deviation for the 3% PG cigarette. An ANOVA single factor analysis showed that the results between the two cigarettes were not statistically different for 95% confidence. The retention of solanesol from the commercial cigarette showed an average of 72.5% with 11.7% relative standard deviation, and the cigarette with 3% added PG showed an average retention of 70.8% with 14.5% relative standard deviation. ANOVA single factor analysis indicated no significant differences in the retention % of solanesol for the two cigarettes at 95% confidence. No correlation was found between the amount of solanesol delivered from the cigarette to the smoker and the solanesol retained %.