Purpose: Inoperable malignant bowel obstruction (MBO), a severe complication of peritoneal carcinomatosis, has a low desobstruction rate (30–40 %) and end-of-life decision-making is hampered by the lack of known prognostic factors. This study aimed to explore prognostic factors for desobstruction in MBO. Methods: All patients with inoperable MBO admitted in our large oncology hospital between 2010 and 2013 were treated following a clinical protocol based on antiemetics, steroids and two antisecretories, octreotide, and hyoscine butylbromide. Two prognostic factor analyses using logistic regressions were performed, one based on data from day 1 of admission and the other on data from day 8. Results: Forty-five patients were included. Frequency of desobstruction was 48.9 %. In the analysis of prognostic factors on day 1, MBO episodes derived from functional physiopathologic mechanisms (vs. mechanic or mixed) were more prone to resolve (p < 0.001 corrected for multiple comparisons). Considering patients alive with persistent obstruction on day 8, a better clinical condition was the variable more associated with desobstruction, but without statistical significance after correction for multiple comparisons. Conclusions: A functional physiopathologic mechanism of MBO development may be an early prognostic factor for desobstruction. A high proportion of desobstruction was observed, suggesting that the combination of antisecretories with different mechanism of action warrants further investigation.