['Elderly, hospitalized patients suffer disproportionately from constipation; however, little data suggest that constipation prophylaxis reduces length of stay (LOS). We performed a retrospective analysis of elderly patients admitted to our hospital with congestive heart failure (CHF) to determine the effects of constipation prophylaxis on LOS.', 'Patients ≥\u200965 years old admitted with the diagnosis of CHF in 2012 were evaluated for home and hospital laxative use on admission. Our primary outcome was LOS. We used linear regression modeling to independently evaluate the impact of constipation prophylaxis on LOS.', 'Among 618 patients who were eligible for our study, 201 (32.5%) were using laxatives at home, whereas 254 (41.1%) were started on a prophylactic laxative on admission. There was no significant difference in LOS between patients receiving prophylaxis versus those who did not (P\u2009=\u20090.32). Patients with home laxative use had a 1 day longer LOS compared to those without laxative use (6 vs 5, P\u2009=\u20090.03). Among patients with home laxative use, there were 2 days longer LOS in those who were not given constipation prophylaxis on admission (8 vs 6, P\u2009=\u20090.002). After multivariate adjustment, failure to use constipation prophylaxis in patients with home laxative use was the only independent predictor of increased LOS (P\u2009=\u20090.03).'] Does constipation prophylaxis reduce length of stay in elderly hospitalized heart failure patients with home laxative use?