The aim of the present study was to compare the effects of water-based aerobic training and water-based resistance training on muscular strength and cardiorespiratory fitness in older women. Sixty-nine individuals were randomized into the following three groups: the water-based aerobic training (WA, n = 23) group, the water-based resistance training (WR, n = 23) group, and the control group (CG, n = 23). Participants were trained two times per week for 10 weeks. The trainings presented a linear periodization with an increase in the volume-intensity relation. Maximal dynamic muscular strength and the cardiorespiratory fitness were evaluated before the start of training and after 10 weeks of training. Only the WA group showed an increase in maximal oxygen consumption (13.8%) and oxygen consumption at the second ventilatory threshold (16.4%). Maximal dynamic strength of knee extensors improved in 10.6% of WA, 8.0% of WR, and 4.7% of CG participants, without any difference between the groups. Maximal dynamic strength of knee flexors was increased in 14.1% of WA and in 17.7% of WR participants; however, it remains unchanged in CG participants. No differences were observed in resting heart rate, peak heart rate, heart rate at the second ventilatory threshold and maximal dynamic strength of shoulder horizontal flexors. It was concluded that WA seems to be more efficient for improvement in cardiorespiratory responses, and both WA and WR were efficient for development of maximal dynamic strength of knee flexion and extension.