The use of synchronized intermittent mandatory ventilation with pressure support ventilation (SIMV + PSV) mode has been discontinued. This study analyzed the association between medical outcomes related to the use of assist-control (A/C) and SIMV + PSV in an intensive care unit. In this observational and retrospective study, modes of ventilation and medical data were collected from electronic medical records for three consecutive years and were related to medical outcomes (mortality), duration of mechanical ventilation, length of hospital stay and the need for tracheostomy. Participants were divided into groups according to the modes of ventilation: A/C and SIMV + PSV. Statistical analyses were performed in the R environment. Alpha = 0.05. The using chi-square, Fisher's exact, Mann-Whitney and Kruskal-Wallis tests were used. 345 adult participants were included; 211/345 (61.16%) were males. Of the participants, 151/345 (43.77%) were on SIMV + PSV and 194/345 (56.23%) were on A/C. The comparative analysis between the modes of ventilation showed no significant differences in length of hospital stay (p = 0.675), duration of mechanical ventilation (p = 0.952), mortality (p = 0.241), failed extubation (p = 0.411) and the need for tracheostomy (p = 0.301). SIMV + PSV as a mode of ventilation showed similar statistical results to the A/C mode, when compared to analyzed medical outcomes.