This study aims to compare muscle activity in the pectoralis major, anterior deltoid, and triceps brachii in the horizontal bench press exercise with a prone grip at 150% and 50% of the biacromial width and the seated chest press exercise with two types of grips (a neutral grip at ~150% of the biacromial width and a prone grip at ~200% of the biacromial width). Twenty physically active adults performed a set of 8 repetitions at 60% of the one repetition maximum. The results showed that the clavicular portion of the pectoralis major had significantly greater muscle activity in the seated chest press exercise with a neutral grip (~30% of the maximal voluntary isometric contraction (MVIC)) than in the lying bench press exercise with a prone grip at 150% of the biacromial width (~25% MVIC). The muscle activity of the anterior deltoid was not significantly different across any exercise or grip evaluated (~24% MVIC). The muscle activity of the triceps brachii was significantly higher in the lying bench press exercise with a grip at 50% biacromial width (~16% MVIC) than at 150% of the biacromial width (~12% MVIC). In conclusion, all exercises and grips showed similar muscle activity, and the selection of these exercises should not be based exclusively on the grounds of muscle activation but rather on the load capacity lifted, the level of technique of the participant, and/or the transference to the specific sporting discipline or event.